The correct answers are:
Who, which and whose are relative pronouns.
It is, a hexagonal, traffic sign.
B.
Jeremy has an old red wagon.
C.
The antique, and enormous clock stands in our living room.
D.
The stereo was designed with four, large speakers.
This question is obviously focused on commas, so if you say these sentences out loud and use breaks after every comma, you can tell which sentence doesn't make sense. So the answer is (d.).
Answer:
develops and supports the key idea of the thesis statement
Explanation: