Which Scenario Is Not an Example of a Prezygotic Isolating

Which scenario is not an example of a prezygotic isolating mechanism?

A) An iris blooms at a different time of the year than a daffodil.
B) A peacock puts on a different mating display than a sparrow.
C) A snail with a shell coiling in one direction cannot mate with a snail whose shell curls in the other direction.
D) A zebroid, a cross between a horse and zebra, is sterile.
E) One type of roundworm would reject the sperm from another species of roundworm.