Which of the Following Is an Example of a Mass

Which of the following is an example of a mass extinction?

A) when a comet delivered water to create the ocean component of the Earth's hydrosphere
B) when mockingbirds, finches, tortoises, and iguanas developed distinct physical differences on the Galapagos Island
C) when dinosaurs died out 65 million years ago, perhaps the result of the impact of a large asteroid
D) when friction with gas molecules causes meteoroids to heat up as they pass through the mesosphere, creating bright, fast-moving "shooting stars"
E) a region in the Earth's crust above the transition zone and upward to the base of the crust where no life exists