Refer to the Scenario Below, and Then Answer the Following

Refer to the scenario below, and then answer the following question(s) .
Species of fruit fly larvae in the genus Rhagoletis each feed on a particular kind of fruit. Rhagoletis pomonella feeds on the small red fruit of the hawthorn tree. In 1865, farmers in the Hudson River valley found that R. pomonella flies had begun attacking their apples and then spread to apple orchards in adjacent areas of Massachusetts and Connecticut. These now separate varieties of flies, the apple and haw flies, usually don't interbreed with each other because their periods of mating coincide with the different ripening times of apples and hawthorn fruit. Each variety is becoming specialized to feed and reproduce in its own particular microhabitat and may be transitioning to separate species.
-If the apple and haw flies no longer interbreed due to the different ripening times of apples and hawthorns,this would be an example of what kind of reproductive isolating mechanism?

A) ecological isolation
B) temporal isolation
C) behavioral isolation
D) mechanical isolation
E) gametic isolation