Answer:
the correct answer is a
ARE BASED ON A SET OF OBSERVATIONS
hope this helps!
Answer:
I think it's
A <u>mass </u>extinction occurs when many species go extinct in a relatively short period of time.
Explanation:
Mass extinction is usually defined as a loss of about three-quarters of all species in existence across the entire Earth over a “short” geological period of time. Hence, I think the answer is correct.
