An explosion of genetic diversity similar to that which occurred during the Cambrian Period hasn't happened recently, most likely because
A) evolution of life on Earth is no longer occurring
B) such an explosion can occur only for simple organisms and not complex ones
C) there are no more ecological niches available to allow this to happen
D) of the widespread presence of efficient predators that make it much more difficult for entirely new organisms to appear

Question

Quizplus · Accepted Answer

The widespread presence of efficient predators in today's ecosystems makes it significantly harder for entirely new organisms to emerge and establish themselves, unlike during the Cambrian Period when ecosystems were less complex and competitive.

An Explosion of Genetic Diversity Similar to That Which Occurred