GRE课程
Questions 1 and 2 are based on this passage
When selecting a nest, the female of the river blenny (a small fish) appears to be sensitive to both size and orientation. Blennies deposit their eggs preferably in nests under large stones and in nests facing southeast. Southeast-facing nests contain larger egg clutches, a fact that cannot be completely explained by differences in nest stone sizes. Moreover, in a recent study, current speeds upstream of the nest and at the nest entrance were similar for nests facing southeast and those facing in other directions. A southeast-facing entrance per se thus seems to be the specific nest feature preferred by females, rather than the effect of selective positioning on current at nest entrance. The reasons for this preference are unclear, however.
The author of the passage considers “current speeds” in order to
identify a factor that undermines the significance of nest stone size for female river blennies
indicate one possible advantage of river blenny nests that do not face southeast
eliminate a possible explanation for a nest orientation tendency among female river blennies
indicate why female river blennies are sensitive to both size and orientation of possible nests
suggest a reason why many female blennies prefer southeast-facing nests
Select one answer choice.
