问题详情

According to the article, the population explosion of elk and deer was caused also by ______.
A．the adoption of a policy of aggressive predator elimination.
B．the increased number of National Parks.
C．the deceasing number of visitors to National Parks.
D．the heavy exploitation of endangered animals in the 20 century.此题为多项选择题。请帮忙给出正确答案和分析，谢谢！