In the 1800s and early 1900s, many American ranchers and farmers moved west. They helped to settle the United States' western territories. The ranchers and farmers wanted to protect their families and livestock, so they killed many predators, including wolves.

Today, there are too many animals such as deer, which were previously hunted by wolves. Scientists are trying to decrease the number of these overpopulated animals by setting up protected areas for wolves to live.

How might this action affect western ecosystems?
A. This action will likely have no effect on western ecosystems.
B. The wolves will bring the deer's population down to a reasonable level.
C. The wolves will cause the deer to become extinct.
D. The wolves will cause western ecosystems to become polluted.