Answer:
The correct answer is External fertilization.
Step-by-step explanation:
Sexual reproduction involves the fusion of male and female gamete, a process called fertilization. This can occur either inside the body called internal fertilization or outside the body called external fertilization. Many marine invertebrates release their gametes in water. The sperms swim to reach the eggs. The process of spawning is observed in aquatic organisms where the female release the eggs and sperms are released by the male at the same time. Fertilization occurs externally in the water bodies.