Final answer:
Hybrid inviability (option c) is not an example of a prezygotic barrier because it occurs after the formation of a zygote and results in the early death of a hybrid organism. Prezygotic barriers prevent fertilization and zygote formation itself.
Correct option is c) Hybrid inviability
Step-by-step explanation:
The question you asked pertains to the distinction between prezygotic and postzygotic barriers in the context of reproductive isolation. Prezygotic barriers are mechanisms that prevent fertilization and therefore reproduction from occurring between two different species. Examples include differences in mating rituals, geographic isolation, and reproductive organ incompatibility. On the other hand, postzygotic barriers occur after the formation of a zygote, such as when hybrid organisms do not survive past the embryonic stage, which is referred to as hybrid inviability, or when hybrids are sterile and cannot reproduce, known as hybrid sterility.
The situation that is not an example of a prezygotic barrier is c) Hybrid inviability. Hybrid inviability pertains to a postzygotic barrier because it occurs after a zygote has been formed and refers to the inability of hybrid organisms to survive through the embryonic stage. Prezygotic barriers, in contrast, prevent fertilization and the formation of a zygote in the first place.