Over the past 500 million years, there have been ________ mass extinctions, and each time, at least ________ of the species on Earth became extinct.
A. two; 25%
B. five; 25%
C. five; 50%
D. twelve; 96%
Answer:C
Over the past 500 million years, there have been ________ mass extinctions, and each time, at least ________ of the species on Earth became extinct.
A. two; 25% B. five; 25% C. five; 50% D. twelve; 96%