How are mountains foam

Which of the following is a possible reason for sleep? a) growth b)digestive c)speed d)intelligence

Would really appreciate it, i have an idea but not completely sure

Next pretest: evolution select the correct answer in a laboratory population of flies, the female flies are gray and the males are yellowish gray. biologists observed that all the male flies had an equal chance for reproduction, but the male flies with the brightest colors were more likely to successfully reproduce. what phenomenon could explain such a change? a sexual selection b. disruptive selection c. stabilizing selection d. directional selection