If Current Changes in Ocean Temperature and PH Caused a Mass

If current changes in ocean temperature and pH caused a mass extinction of today's reef-building organisms, we would see:

A) an unprecedented mass extinction, unlike anything Earth has experienced in the past.
B) one more in a series of mass extinctions that have wiped out reefs at least three times since the first reefs appeared over 500 million years ago.
C) one more in a series of mass extinctions that have wiped out reefs at regular intervals-roughly every 10 million years since the first reefs were formed over 500 million years ago.
D) the second great mass extinction of reefs; the only previous such extinction took place at the end of the Permian.
E) None of the answer options is correct.