A Man in the Trobriand Islands Works Hard in His

A man in the Trobriand Islands works hard in his garden to produce yams.Which of the following demands is he satisfying?

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