Speciation is the evolution of reproductive isolation between two populations. How could coevolution ...

Speciation is the evolution of reproductive isolation between two populations. How could coevolution be-tween Glochidion trees and Epicephala moths lead to speciation in Glochidion?
 
  a. Genetic drift in allopatric populations changes pollen properties so that cross-pollination by moths upon secondary contact no longer results in seeds.
  b. Epicephala moths adapt physiologically to different flight temperatures in two allopatric habi-tats and will die when switching habitats.
  c. Epicephala moths in different habitats adapt to different changes in the smell of flowers.
  d. None of the above.