The correct answer is A. Birds of prey that eat mice will become more numerous.
Step-by-step explanation:
An increase in the population of mice implies there is increased availability of food for mice predators including some birds of prey. At the same time, more food for birds of prey would help this species to better survive and reproduce, which would likely increase the number of birds of prey after some time. Moreover, the increase of mice and birds of prey occurs because these species belong to the same food chain and an increase/decrease in one species affects the other. According to this, the expected result is "Birds of prey that eat mice will become more numerous".