Answer:
b. Producing gametes (sperm and egg cells) that unite inside the female reproductive system.
Step-by-step explanation:
The "gametes" refer to the sex cells in humans. The female sex cells are called "egg cells" and these are being produced by the ovary. The male sex cells are called "sperm cells" and these are being produced by the testicles. After copulation, there's a probability for the egg cells and sperm cells to unite. They unite inside the female's reproductive system, specifically inside the "fallopian tube."