Your answer would be <em><u>D. refrigerator coils keeping the refrigerator cold</u></em>
The forelimbs of all mammals are homologous traits, meaning that they originate from a common ancestral trait.
The correct answer is therefore C. Homologies (homologous traits), from the same common ancestor.
(To clarify, we know it is from a common ancestor because both bats and humans are mammals)
Explanation:
It stretched or compresses the sound waves it is producing if it is relatively moving away to getting closer respectively. This is called the <u>Doppler shift effect</u>..
This is why when a wailing ambulance approached you, the pitch of its wailing is high but when it passes you and moves away from you the pitch of the wailing lowers. Remember this is happening relative to your position.