What question does Zinkoff have trouble answering?

If your question pertains to Chapter 18, Zinkoff has difficulty answering the question, —Who is your best friend?

Until he comes to this question—Who is your best friend?—and that blank space seems to be saying to him: If you don’t have one, you’d better get one.

He skips over the question to finish the rest of the test. He returns to it. Time is passing. Pretty soon Mrs. Shankfelder will say, “Pencils up.”
Best friend . . . best friend . . .
“One more minute,” says Mrs. Shankfelder, who does not usually give a warning. He panics. He looks around the classroom, too bad if the teacher thinks he’s cheating.