Using the diagram, sexual reproduction is illustrated in

The diagram is illustrating sexual reproduction in option I. In this option, there are two different individuals, one male and one female, each contributing genetic material to create offspring. The male and female individuals are indicated by the labels "♂" and "♀" respectively. The fusion of the male and female gametes (sperm and egg) produces a zygote, which then develops into an offspring with a unique combination of genetic material from both parents. This process is characteristic of sexual reproduction. Therefore, option I is the correct answer.