akanshaxo wrote:
Ecologist: Before finding a mate, male starlings decorate their nests with fragments of aromatic plants rich in compounds known to kill parasitic insects. Since these parasites are potentially harmful to nestlings, some researchers have hypothesized that the function of these decorations is nestling protection. However, males cease to incorporate such greenery once egg laying starts, which suggests instead that the function of the decorations is to attract females.
Which one of the following, if true, most strengthens the support for the ecologist's conclusion?
(A) Adult starlings are able to defend themselves against parasitic insects.
(B) Male starlings do not decorate their nests in areas with unusually small populations of parasitic insects.
(C) Nestlings grow faster in nests that incorporate aromatic plants than in nests that do not.
(D) Male starlings tend to decorate their nests with a greater number of aromatic plants when a caged female is positioned adjacent to the nest.
(E) The compounds in the aromatic plants used by the male starlings to decorate their nests are harmless to nestlings.
LSAT Question
Conclusion: Decoration is done to attract females and not to kill parasitic insects.
We need to focus on the options that support attracting females.
(A) Adult starlings are able to defend themselves against parasitic insects.
Not relevant.
(B) Male starlings do not decorate their nests in areas with unusually small populations of parasitic insects.
This is against what the conclusion says. If this were true then decoration was being done to kill the insects.
(C) Nestlings grow faster in nests that incorporate aromatic plants than in nests that do not.
Not relevant. Growth is not being discussed here.
(D) Male starlings tend to decorate their nests with a greater number of aromatic plants when a caged female is positioned adjacent to the nest.
Correct. If the female is near then decoration is at a grander scale to attract her.
(E) The compounds in the aromatic plants used by the male starlings to decorate their nests are harmless to nestlings.
Not relevant.
Hence D is the correct answer.