A Gift-Giver's Efficient Number of Gifts (To Give to a Gift-Recipient)has

Multiple Choice

A gift-giver's efficient number of gifts (to give to a gift-recipient) has fallen from 10 to 8.This could be because

A) the gift-giver's marginal benefit curve for giving gifts shifted down and left.
B) the gift-giver's marginal cost curve of giving gifts shifted up and left.
C) the gift-recipient "fell out" of the gift-giver's utility function.
D) a and b
E) none of the above