What Would Be the Most Convincing Evidence That an Extraterrestrial

Multiple Choice

What would be the most convincing evidence that an extraterrestrial event had led to a climatic change that resulted in extinction of a group of organisms?

A) Evidence that climate change was gradual,taking place over the course of a few thousand years
B) An increase in oxygen levels during the event
C) A decrease in oxygen levels during the event
D) High iridium concentrations found in a thin layer separating rocks from before and after the event
E) High sulfur concentrations found in a thin layer separating rocks from before and after the event