Final answer:
The first generation of offspring from the cross of parent plants is known as the F1, or first filial, generation. It follows the parental (P) generation and precedes the F2, or second filial, generation. The correct option is D : F₁.
Step-by-step explanation:
When parent plants are crossed, scientists refer to the first generation of offspring as the F1, or the first filial generation. These offspring arise from the cross of the P generation, or the parental generation. The term 'filial' is derived from the Latin word 'filius' or 'filia' which means son or daughter, respectively, denoting that the F1 generation consists of the 'children' of the original parents. Once the characteristics of the F1 generation are examined, they can then be allowed to self-fertilize to produce the F2 generation, or the second filial generation.
Gregor Mendel, the father of genetics, used the P, F1, and F2 generations to conduct experiments and formulate his laws of inheritance, with the ratios of characteristics in the P, F1, and F2 generations providing crucial insights into the mechanisms of heredity.