It Is Difficult to Estimate Current Rates of Extinction, but We

It is difficult to estimate current rates of extinction, but we know that extinction rates have risen dramatically in recent years because

A) most species in danger of extinction are microscopic.
B) background extinction rates have increased.
C) the fossil record is unreliable.
D) current rates of extinction are much higher than that of background rates.
E) new species are evolving as fast as species are becoming extinct.