Answer:
D decrease because fewer plants would be available as food
Explanation:
According to this question, Bison is a primary consumer that feeds on grass in a prairie ecosystem while wolves are secondary consumers that feed on the Bisons. The occurence of a drought i.e. Lack of water, will cause natural vegetation to reduce drastically.
The carrying capacity (average population size) of bisons will decrease in the ecosystem because fewer plants would be available as food for them as primary consumers.
