The correct answer is (A).
Pollen Analysis and the Irish Landscape
Step 1: Read the Passage Strategically
Sample Highlighting
In tracing the changing face of the Irish landscape, scholars have traditionally relied primarily on evidence from historical documents. However, such documentary sources provide a fragmentary record at best. Reliable accounts are very scarce for many parts of Ireland prior to the seventeenth century, and many of the relevant documents from the sixteenth and seventeenth centuries focus selectively on matters relating to military or commercial interests.
Studies of fossilized pollen grains preserved in peats and lake muds provide an additional means of investigating vegetative landscape change. Details of changes in vegetation resulting from both human activities and natural events are reflected in the kinds and quantities of minute pollen grains that become trapped in sediments. Analysis of samples can identify which kinds of plants produced the preserved pollen grains and when they were deposited, and in many cases the findings can serve to supplement or correct the documentary record.
For example, analyses of samples from Long Lough in County Down have revealed significant patterns of cereal-grain pollen beginning by about 400 A.D. The substantial clay content of the soil in this part of Down makes cultivation by primitive tools difficult. Historians thought that such soils were not tilled to any significant extent until the introduction of the moldboard plough to Ireland in the seventh century A.D. Because cereal cultivation would have required tilling of the soil, the pollen evidence indicates that these soils must indeed have been successfully tilled before the introduction of the new plough.
Another example concerns flax cultivation in County Down, one of the great linen-producing areas of Ireland during the eighteenth century. Some aspects of linen production in Down are well documented, but the documentary record tells little about the cultivation of flax, the plant from which linen is made, in that area. The record of eighteenth-century linen production in Down, together with the knowledge that flax cultivation had been established in Ireland centuries before that time, led some historians to surmise that this plant was being cultivated in Down before the eighteenth century. But pollen analyses indicate that this is not the case; flax pollen was found only in deposits laid down since the eighteenth century.
It must be stressed, though, that there are limits to the ability of the pollen record to reflect the vegetative history of the landscape. For example, pollen analyses cannot identify the species, but only the genus or family, of some plants. Among these is madder, a cultivated dye plant of historical importance in Ireland. Madder belongs to a plant family that also comprises various native weeds, including goosegrass. If madder pollen were present in a deposit it would be indistinguishable from that of uncultivated native species.
Passage Notes
Paragraph 1
Scholars rely on hist. docs to trace hist. of land
Hist. docs not so reliable
Paragraph 2
Pollen fossils an add'l way to track changes
What pollen grains can show
Paragraph 3
Ex: cereal pollen in Co. Down
Historians: soils not tilled before 7th C.
Cereal pollen = soil was tilled before 7th C.
Paragraph 4
Ex: flax pollen in Co. Down
Doc. record scarce on flax
Historians: flax grown pre-18th C.
Pollen: flax grown only since 18th C.
Paragraph 5
Limits on pollen's ability to show hist.
Ex: madder
Pollen can't disting. madder from other species
Discussion
Paragraph 1 of this Natural Science passage introduces limitations on the traditional study of Ireland's landscape: accounts of the landscape are scarce, and where they do exist, they are incomplete. That provides our Topic (the historical Irish landscape), but Scope and Purpose are still wide open.
Paragraph 2 introduces a supplemental source of information that will eventually become the Scope of the passage: studies of fossilized pollen grains, and what they can tell us about changes in the landscape. The paragraph outlines the information pollen grains can provide about the vegetative history of a region, and then relates that information to the historical record. The author seems to value the pollen evidence for its ability to "supplement or correct" the historical record.
Paragraphs 3 and 4 provide examples of how pollen grain information has changed beliefs about some aspects of historical land development. Don't worry too much about the details of these paragraphs—you can come back to them if a question asks you to.
Finally, paragraph 5 notes that pollen analysis isn't without its own limitations and gives an example. It's not until the end that we can be sure of the author's Purpose, which is largely informative: to explain the impact of a new information source on our understanding of the evolution of the Irish landscape. The Main Idea reflects this: The author believes that studies of fossilized pollen can be useful for supplementing or correcting the historical record when studying changes in Ireland's landscape.
(A) Global
Step 2: Identify the Question Type
Any question asking for the "main point" of the passage is a Global question.
Step 3: Research the Relevant Text
The entire passage is relevant in a Global question. Use your knowledge of the passage's big picture (Topic, Scope, Purpose, Main Idea) to predict your answer.
Step 4: Make a Prediction
As you know from Step 1, the Main Idea of the passage is that fossilized pollen records can sometimes help make more accurate determinations than can the historical record when it comes to the development of the Irish landscape.
Step 5: Evaluate the Answer Choices
(A) is a match for this prediction.
(B) is a Distortion. The analysis of historical documents is what led historians to their mistaken hypotheses in the first place.
(C) incorrectly shifts the passage's focus from the historical development of Ireland's landscape to the identification of plant species. Furthermore, the second sentence of the last paragraph tells you that pollen analysis can't identify the species of some plants.
(D) misuses some of the passage's details. The idea that cultivation of cereal, flax, and madder had a significant impact on the Irish landscape was never in question.
(E)'s phrase "severely limited" is Extreme, and its tone is all wrong. The author presents the pollen analysis as a valuable additional tool, even though it has some limitations.
