What was the reason that Josiah, Sheku and Ishmael do training exercises with a banana tree?

A) Because they run out of ammunition for the AK-47s.

B) Because stabbing the banana tree was easier and less intimidating.

C) Because AK-47s were big, heavy and difficult to handle for Josiah and Sheku.

D) Because learning to stab was the first exercise, putting magazines was second and the last exercise was to learn how to fire an AK-47s.