Answer:
The correct answer is option c. "The gametes must be kept wet to avoid desiccation".
Step-by-step explanation:
External fertilization is an adaption were species reproduce sexually, but there is no direct contact between the female and the male species, because the egg is fertilized outside the female's body. This adaptation occurs more often in aquatic animals because the gametes must be kept wet to avoid desiccation and allow fertilization, which occurs much more easily on aquatic environments.