The most probable and most likely answer to this problem would be C. revealed much about their behavior.
Out of the four options presented in this problem, C. would only need a complete subject to make it a correct sentence. Options A. by closely watching and gathering data and B. to terrifying effect would probably need other more words and/or phrases to make them more complete. D. insect studies, on the other hand, can also be considered as a correct option IF insect become the subject.
The right answer for the question that is being asked and shown above is that: "<span>"Many people assume that germline engineering is necessary to allow couples at risk of passing on a genetic disease to avoid doing so. This is not so."</span>
Answer:
I can't do that because that would be cheating
Explanation:
A. !
"What an exciting trip!"
The speaker shows enthusiasm when saying this and exclaims it.