Question

A scientist tries to mate the two similar-looking fruit flies Drosophila melanogaster and Drosophila simulans. But he finds that they are unable to produce viable offspring. What kind of evolutionary barrier could this be? A. Chromosomal B. Postzygotic C. Physical

Answer 1

as the question hints viable offspring the answer must be B. they cant mate if the barrier is physical. if chromosomal there will be no offspring

Answer 2

B postzygotic. they're stating that they can't produce VIABLE offspring, which means they CAN produce offspring, but they don't survive