Question

male howler monkeys are known for their deep, booming calls, which can be heard from miles away. researchers have found that male howler monkeys call most frequently at dawn and dusk, when rival groups are most likely to be active. the calls serve as a warning to other monkeys to stay away. scientists believe that this behavior is an energy - saving strategy, as vocal displays help establish dominance without the need for direct confrontations. which choice best states the main idea of the text? choose 1 answer: a male howler monkeys call most often at dawn and dusk, when rival groups are also likely to be active. b howler monkeys are known for their loud calls, which can be heard from miles away. c howler monkey calls are louder than the calls of most other monkey species. d male howler monkeys use their loud calls to warn off other monkeys and conserve energy.

Explanation:

The text first introduces male howler monkeys' calls, then mentions when they call (dawn and dusk), and finally explains the purpose of the calls (warning others and energy - saving). Option A only mentions the time of calling; Option B only states a fact about the calls' loudness; Option C has no basis in the text as there's no comparison with other monkey species. Option D combines the warning function and the energy - saving aspect, which covers the main idea.

Answer:

D. Male howler monkeys use their loud calls to warn off other monkeys and conserve energy.