Mark the correct statement (with respect to the Mendelian dihybrid cross where the two parents differed in two pairs of contrasting traits : seed color and seed shape).

Options

A. 3 / 4th of `F_(2)` plants have green seeds and 1/4th have yellow
B. Mendel cross-hybridized `F_(1) ` plants and got 9 : 3 : 3 : 1 phenotypic ratio
C. In `F_(2)` generation, round and wrinkled seed shape segregates just like in a mohohybrid cross
D. Parental phenotypic ratio is 1 : 1 in `F_(2)` generation

Answer

To solve the question regarding the Mendelian dihybrid cross involving seed color and seed shape, we can break down the solution into the following steps:

### Step-by-Step Solution:

1. **Understand the Dihybrid Cross**:
- A dihybrid cross involves two pairs of contrasting traits. In this case, we are considering seed color (yellow vs. green) and seed shape (round vs. wrinkled).

2. **Identify the Parental Genotypes**:
- The first parent (homozygous dominant) has round yellow seeds, which can be represented as RRYY (where R = round, Y = yellow).
- The second parent (homozygous recessive) has wrinkled green seeds, represented as rryy (where r = wrinkled, y = green).

3. **F1 Generation**:
- When these two parents are crossed, all offspring in the F1 generation will be heterozygous (RrYy) and will exhibit the dominant traits: round shape and yellow color.

4. **Selfing the F1 Generation**:
- The F1 plants (RrYy) are then self-fertilized to produce the F2 generation. This involves a cross between two RrYy individuals.

5. **F2 Generation Phenotypic Ratio**:
- The phenotypic ratio in the F2 generation for a dihybrid cross is typically 9:3:3:1. This means:
- 9 will have round yellow seeds,
- 3 will have round green seeds,
- 3 will have wrinkled yellow seeds,
- 1 will have wrinkled green seeds.

6. **Evaluate the Given Statements**:
- Now, we need to analyze the provided statements in the question regarding the F2 generation and identify which one is correct based on the principles of Mendelian genetics.

7. **Correct Statement**:
- The correct statement is that in the F2 generation, round and wrinkled seed shapes segregate in a manner similar to a monohybrid cross, which yields a ratio of 3:1 for the seed shape.

### Conclusion:
The correct statement regarding the Mendelian dihybrid cross is that in the F2 generation, round and wrinkled seed shapes segregate just like a monohybrid cross, confirming the law of independent assortment.