Which of the following scenarios is an example of temporal isolation? A.

Fossil evidence suggests that a number of members of one squirrel species evolved over time into two separate species, each on opposite sides of the Grand Canyon.

B.

Black-eyed Susans and daisies used to be part of the same species. A random mutation in a subset of a population caused one group to release their pollen three weeks before the other, causing interbreeding to cease.

C.

Two species of tree crickets live in a Costa Rican dry forest. Their habitats and ranges overlap. The two species never interbreed because the calls of the males are different and do not attract females of the other species.

D.

Indian paintbrush flowers vary greatly in color. Bumblebees form a search image for the most average common color and preferentially pollinate those flowers.