As seen in the video The Trobriand Islanders and discussed in lecture, why did Boonamiga pledge to grow a big yam garden?

He was competing for prestige.

He wanted to make a big profit from selling yams.

He wanted yams to give to Chief Malibutal, to help convince the chief to become his political ally.

He needed yams to repay his kula ring partner for the shell jewelry he had received.

He needed more yams to meet the subsistence needs of his growing family.