Answer
a.
Work Step by Step
For sexual reproduction to occur, there must be a meeting of male and female gametes. To form gametes, meiosis must occur; this process creates descendant cells with half the number of chromosomes as the parent cells. During fertilization, a new organism is created when the two gametes unite, thus restoring the original number of chromosomes; the offspring has a unique combination of traits that comes from both parents. Vertebrates are not the only types of organisms that engage in sexual reproduction.
