Question

what is extinction? when an allele is removed from a population when a population moves out of an ecosystem when a species is completely removed or completely dies out

Explanation:

Extinction refers to the complete disappearance of a species from the Earth. It means that there are no more individuals of that species alive. The first option about an allele being removed is about genetic change within a population, not species - level extinction. The second option about a population moving out is just migration, not extinction. The third option correctly describes extinction as the complete removal or death - out of a species.

Answer:

when a species is completely removed or completely dies out