Which of these describes an example of a keystone species that scientists should make efforts to protect?
A. more than 1,000 newly hatched wood frog eggs in a forest ecosystem
B. a gopher tortoise that provides a home to more than 300 different species of animals in its burrow
C. a nonnative population of lionfish living on a coral reef in Florida that have no natural predators
D., a population of mistletoe plants that are parasitic because they depend on other trees and plants in the ecosystem in order to get what they need to survive