The answer to your question is With a loud chirping sound, the children heard baby chicks squawk.
This is your answer because the phrase is supposed to be of baby chicks chirping nice and softly, but instead it gives the impression of a little baby bird just squawking, like a duck, but do you really think that a baby chick can squawk?
Therefore your answer is D. With a loud chirping sound, the children heard baby chicks squawk.
I hope that this has satisfied you.
