Under which of the following conditions will speciation not occur?
a. logging operations in a forest cut a single population of beetles in two so that they can no longer mix.
b. some snails in a population develop shells that twist to the right instead of the left, which makes mating impossible with partners of opposite shell shape.
c. a newly constructed housing development divides the habitat of a bird species in two, forcing the birds to fly from one section to the other
d. some females of a species of spider prefer to mate with males that have red markings while other females prefer