In tracing the changing face of the Irish landscape, scholars ... ...

The passage indicates that prior to the use of pollen analysis in the study of the history of the Irish landscape, at least some historians believed which one of the following?
(A) The Irish landscape had experienced significant flooding during the seventeenth century.
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in Free Sample 1: Moderate Passage