TPO11 Begging by Nestlings Q5 - 英檢

Paragraph 2：Further evidence for the costs of begging comes from a study of
differences in the begging calls of warbler species that nest on the ground
versus those that nest in the relative safety of trees. The young of
ground-nesting warblers produce begging cheeps of higher frequencies than do
their tree-nesting relatives. These higher-frequency sounds do not travel as
far, and so may better conceal the individuals producing them, who are
especially vulnerable to predators in their ground nests. David Haskell
created artificial nests with clay eggs and placed them on the ground beside
a tape recorder that played the begging calls of either tree-nesting or of
ground-nesting warblers. The eggs “advertised” by the tree-nesters' begging
calls were found bitten significantly more often than the eggs associated
with the ground-nesters' calls.

5. The experiment described in paragraph 2 supports which of the following
conclusions?
○ Predators are unable to distinguish between the begging cheeps of
ground-nesting and those of tree-nesting warblers except by the differing
frequencies of the calls.
○ When they can find them, predators prefer the eggs of tree-nesting
warblers to those of ground-nesting warblers.
○ The higher frequencies of the begging cheeps of ground-nesting warblers
are an adaptation to the threat that ground-nesting birds face from predators
○ The danger of begging depends more on the frequency of the begging cheep
than on how loud it is.


正確答案是c，為什麼？ 原文沒有說到高頻率是為了因應危險.

--