You are presented with the quiz "What increases genetic diversity?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "sexual reproduction increases genetic diversity" and "mammals are dioecious with sexual reproduction and internal fertilization". So, what's the best answer to the question?

(1). By coral exoskeletons (2). Something that waters do (3). Something that planets do (4). fertilization (5). Something that rocks do (6). deoxyribonucleic acid (7). Males and females (8). Somethign that mammals do.
The answer is:
(8).