How common has extinction been in the fossil record?
A) Over 99 percent of all past species have become extinct.
B) Roughly 50 percent of all past species have become extinct.
C) Roughly 25 percent of all past species have become extinct.
D) Very few species have ever become extinct.
A) Over 99 percent of all past species have become extinct.
B) Roughly 50 percent of all past species have become extinct.
C) Roughly 25 percent of all past species have become extinct.
D) Very few species have ever become extinct.