In europe, three lineages of bears evolved from a common ancestor. two of those lineages led to present-day black bears and brown bears. the third lineage led to cave bears that went extinct 24,000 years ago. which of the following could explain why only one group of bears went extinct? a. individual cave bears must not have been able to adapt to changing conditions as quickly as brown or black bears. b. one group of bears was less highly evolved than the other two groups and was destined to die out. c. some environmental change severely threatened cave bear survival but not the survival of brown or black bears. d. random chance led to the extinction of cave bears and survival of brown and black bears.