Based on the information provided, which of the following factors was responsible for the population reduction?

Animal populations are regulated by a variety of natural factors. Five of these factors are:

✑ competition―A struggle among rival organisms results when available resources

(for example, food or shelter) are limited. ✑ predation―Many animals pursue and eat other animals as prey. ✑ disease―In overcrowded populations, the buildup of waste products contributes to

the easy spread of disease. ✑ stress―In some populations, overcrowding can lead to hormonal disorders, which can cause abnormal behavior, thereby limiting the population. ✑ natural disaster―The occurrence of storms, floods, and earthquakes can significantly affect a population’s size.

✑ During the Middle Ages, the human population of Western Europe was severely reduced by a combination of unsanitary conditions and the abundance of flea-infested rats that spread the plague.

Based on the information provided, which of the following factors was responsible for the population reduction?
A . competition
B . predation
C . disease
D . stress
E . natural disaster