adkikani Please see my comments in green.
Can you advise why (D) is incorrect?
Boreal owls range over a much larger area than do other owls of similar size. Scientists have hypothesized that
it is scarcity of prey that leads the owls to range so widely. This hypothesis would be hard to confirm directly, since it is not possible to produce a sufficiently accurate count of the populations of small mammals inhabiting the forests where boreal owls live. Careful study of owl behavior has, however, shown that
boreal owls do range over larger areas when they live in regions where food of the sort eaten by small mammals is comparatively sparse. This indicates that the scientists’ hypothesis is not sheer speculation.
Boreal owls range over a much larger area than do other owls of similar size.
Background factsScientists have hypothesized that it is scarcity of prey that leads the owls to range so widely.
The claim of scientists.This hypothesis would be hard to confirm directly,
(author's opinion, main conclusion)since it is not possible to produce a sufficiently accurate count of the populations of small mammals inhabiting the forests where boreal owls live.
(premise supporting above claim)
Careful study of owl behavior has,
however, shown that boreal owls do range over larger areas when they live in regions where food of the sort eaten by small mammals is comparatively sparse.
Counter-premise to author's claim but supports Scientists hypothesis This indicates that the scientists’ hypothesis is not sheer speculation.
Main Conclusion Quote:
D. The first describes a position that the argument opposes; the second presents evidence to undermine the support for the position being opposed.
BF1: Yes author does oppose the claim of scientists by saying it is hard to confirm the claim by direct evidence.
The first part is not True as Argument in whole does not oppose the HypothesisBF2 : the second presents evidence (refer 1)
The second part is not True as well On the Other hand option B
B. The first presents an explanatory hypothesis; the second presents evidence tending to support this hypothesis.
The first indeed presents a hypothesis.
The second presents evidence ( where food of the sort eaten by small mammals is comparatively sparse) to support the hypothesis
Hence Option B is right.
Take Away: When dealing with Bold Face questions identify the Main Conclusion and the Main point.This always helps in identifying the Bold faced statements.
Hope this helps! Let me know if you still need any clarification