If T represents the gene for tallness while t represents dwarfnessThe genotypic ...

In this question, we are asked about the genotypic ratio of the second filial generation, which refers to the offspring of the first generation.

The question mentions two different genes: T for tallness and t for dwarfness. These genes determine the height of the plants.

To understand the genotypic ratio, we need to consider the possible combinations of these genes in the offspring.

In the first filial generation (the offspring of the parents), there are two possible combinations: TT (homozygous tall), and Tt (heterozygous tall).

When these plants reproduce and produce the second filial generation, there are four possible combinations of genes: TT, Tt, Tt, and tt.

Now, let's analyze the options given in the question.

Option A states that the genotypic ratio is 3:1. This means that out of the four possible combinations, three will be tall (TT and two Tt) and one will be dwarf (tt). This is the correct answer.

Option B states a ratio of 1:2:1. This means that out of the four possible combinations, one will be tall (TT), two will be intermediate (Tt), and one will be dwarf (tt). This is not the correct answer.

Option C states a ratio of 2:2. This means that out of the four possible combinations, two will be tall (TT and Tt), and two will be dwarf (tt). This is not the correct answer.

Option D states a ratio of 4:0. This means that all four possible combinations will be tall (TT and three Tt), and there will be no dwarf plants. This is not the correct answer.

Therefore, the correct answer is Option A, with a genotypic ratio of 3:1.