To solve this problem, we need to identify the diagram that represents the production of gametes by the parents, formation of zygotes, and the $F_1$ and $F_2$ generations.$\newline$This diagram is commonly used in genetics to predict the outcome of a particular cross or breeding experiment.$\newline \bullet$The correct diagram for this purpose is the Punnett square.$\newline$Let's understand why the Punnett square is the correct choice:$\newline \bullet$A Punnett square is a grid system used to determine the possible genotypes of offspring from a cross between two individuals.$\newline \bullet$It helps visualize how alleles from each parent combine to form the genotype of the offspring.$\newline \bullet$The rows and columns of the square represent the gametes from each parent, and the cells show the possible zygote combinations.$\newline$Therefore, the correct option is Option 3: Punnett square.