Question

which of these is the best description of a mass extinction? when the numbers of a certain species become less and less over time until they become extinct when a huge event happens to the earth and suddenly causes a large percentage of species to die out when the population of a species starts to get lower but then rebounds and comes back

Explanation:

A mass - extinction is defined as a widespread and rapid decrease in the biodiversity on Earth, typically caused by a major catastrophic event that leads to the extinction of a large proportion of species. The first option describes normal extinction of a single species over time, and the third option describes population fluctuation rather than extinction.

Answer:

when a huge event happens to the earth and suddenly causes a large percentage of species to die out