Use quotation marks [ “ ” ] to set off material that represents quoted or spoken language. Quotation marks also set off the titles of things that do not normally stand by themselves: short stories, poems, and articles. Usually, a quotation is set off from the rest of the sentence by a comma; however, the typography of quoted material can become quite complicated. Hope that helped
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.
My first guess would be that it is an independent clause. This is just a single statement.
There would be a colon after the word phone