50. Which of the following is an act of “paying it forward”?
(A) Tim helped Judy cheat on the test because she was his good friend.
(B) Tim was asked to take care of his younger sister by his mother.
(C) Tim helped an old lady walk across the street, and later on, the old lady shared herfood with a beggar (乞丐).
(D) Tim bought some wristbands from the Pay It Forward Foundation and sold themto his friends.