Answer:
Option C, biologists concerned about the parks ecosystem
Explanation:
It were the biologist during the regime of congress in 1966 who first suggested that gray wolves should be reintroduced to yellow stone. They were concerned about the rising elk population in the Yellow Stone which was causing extreme losses to the ecology . After wolves reintroduction, Wolves started feeding on deer which reduced grazing activity and hence the beavers could get grasses and farmland to re flourish which started killing more elk and hence led to re flourishing of Yellowstone
