The production of gametes by the parents, formation of zygotes, the F₁ and F₂ plants, can be understood from a diagram called:

The correct option is D Punnet square
Punnet square is a graphical representation to calculate the probability of all possible genotypes of offspring in a genetic cross.
It was developed by a British geneticist, Reginald C. Punnett.
The possible gametes are usually written on the top row and left column. All possible combinations are represented in boxes below within the squares, which generates a square output form.
The production of gametes by the parents, the formation of the zygotes, the F₁ and F₂ plants can be understood from a Punnett square.