I would agree with you - the conclusion should leave readers with an important thought at the end.
This thought should never be new, or opposing to the previous ideas you had been writing before. It also shouldn't be confusing, but quite conversely - it should explain everything and put everything in place.
If you are sorting by last name it is B Jenny Douglas.
if you are sorting by first name it is A Denise Thomas
D, "their." Since you're talking about two of them, it's plural. The sentence:
Neither Carol nor Ellen would hesitate to share their supplies with you.
The answer is D..... but it is also found in the end of the first paragraph