What Traditional, Ritual Circumstance Prevents Ezeulu from Giving Umuaro Permission

What traditional, ritual circumstance prevents Ezeulu from giving Umuaro permission to harvest the yam crop?

A) Obika's death renders the yam harvest impure, and therefore not to be eaten.
B) He has not eaten the ritual yams left over from the last harvest.
C) Obika ate the ritual yams left over from the last harvest instead of him.
D) He ate the ritual yams left over from the last harvest too quickly.