Elk are members of the deer family. These herbivores move in herds from the high mountain pastures to the lower valleys and wooded areas throughout the seasons. Their fur color ranges from gray to dark brown which allows them to blend into the dense wooded areas. Natural enemies of the elk include bears, cougars, wolves, and coyotes. The graph below shows how the number of elk in an area has changed over time. Based on the data, one student concludes that an elk predator was introduced into the area during this time period. Which of the following is a likely alternate explanation for the change in the elk population? A. Elk prey increased in the area.

B. The temperature of the area remained constant

C. Elk parasites decreased in the area.

D. The amount of plants in the area decreased.