B. Segregation.
I have the same question and answered it and this is what it told me. I think it should be right.
An eon is 1.05 billion years and an era is 350 million years
Answer:
Gene flow.
Explanation:
When individuals migrate, alleles can be transferred from one population to another population which is known as gene flow. Gene flow is also called gene migration, the introduction of genetic material through interbreeding from one population of organisms to another which changes the composition of the gene pool of the migrated population of organisms. This gene flow creates a new species that is different from previous population of organisms