An Hypothesis About the Sudden End of the Younger Dryas

An hypothesis about the sudden end of the Younger Dryas interval says that a comet struck Earth or exploded in the atmosphere about 12,800 years ago, triggering a series of events that included all the following EXCEPT

A) the collapse of the Clovis culture.
B) a global warming event that lasted several centuries.
C) possible significant reduction in human populations in many areas.
D) possible extinction of the large mammal populations in many areas.