A Species of Mouse Mainly Eats Grasses

Multiple Choice

A species of mouse mainly eats grasses.Individuals of this species are smaller in locations where it co-occurs with a second,larger rodent species that also eats grass than in locations without that larger rodent.What is the most likely cause of this difference?

A) A trophic cascade
B) An evolutionary arms race
C) A mutualism evolving into a consumer-resource relationship
D) A consumer-resource relationship evolving into a mutualism
E) Resource partitioning