What impelled the boy to take so much trouble to spare the feelings of a stranger?

What impelled the boy to take so much trouble to spare the feelings of a stranger?

A.Why did the boy trouble himself to save stranger?

B.Why did the boy try so hard to make friends with a stranger?

C.Why did the boy try his best to build up the confidence of a stranger?

D.Why did the boy make such great efforts in order not to embarrass a stranger?

正确答案是D