When a Man Works Hard in His Garden in the Trobriand

When a man works hard in his garden in the Trobriand Islands to produce yams,he does this to satisfy which of the following demands?

A) to have food for his household to eat
B) to gain prestige by giving yams away to his sister's husbands
C) to prove to his wife that he can work as hard as she can
D) to give the yams to his wife so that she can trade them for goods that they don't produce themselves
E) to trade for fish