Which of the Following Is Considered a Likely Explanation for the Events

Which of the following is considered a likely explanation for the events of the Cambrian explosion?

A) A great surge of volcanic activity was triggered by significant movements of the continental plates and possibly by an asteroid impact.
B) The massive growth of swamp vegetation depleted the atmosphere's carbon dioxide and eventually cooled the Earth's climate.
C) Complex predator- prey relationships and increased atmospheric oxygen levels promoted animal diversification.
D) Solar flares led to increased UV radiation intensity,which in turn promoted a high rate of mutation.This led to rapid diversification of animals.