Test cross of dihybrid ratio is `1:1:1:1.` It proves that

Options

A. `F_(1)` hybrid produces four different gametes
B. `F_(1)` hybrid is homozygous
C. Two different progenies are produced by `P_(1)` parent
D. None of the above

Answer

To solve the question regarding the test cross of a dihybrid ratio being `1:1:1:1`, we need to analyze the implications of this ratio in the context of genetics.

### Step-by-Step Solution:

1. **Understanding Test Cross**: A test cross is a genetic cross between an individual with an unknown genotype (often a heterozygous individual) and a homozygous recessive individual. This is done to determine the genotype of the first individual by observing the phenotypes of the offspring.

2. **Dihybrid Cross Basics**: In a dihybrid cross, we are dealing with two traits, each controlled by different genes. The F1 generation from a dihybrid cross (e.g., AaBb) can produce four types of gametes: AB, Ab, aB, and ab.

3. **Gamete Formation**: If the F1 hybrid (AaBb) is crossed with a homozygous recessive parent (aabb), the offspring can be analyzed based on the gametes produced. The F1 hybrid will produce four different gametes (AB, Ab, aB, ab), while the homozygous recessive parent will only produce one type of gamete (ab).

4. **Offspring Ratios**: When the F1 hybrid (AaBb) is crossed with the homozygous recessive (aabb), the expected offspring phenotypic ratio will be:
- 1 AB (dominant for both traits)
- 1 Ab (dominant for the first trait, recessive for the second)
- 1 aB (recessive for the first trait, dominant for the second)
- 1 ab (recessive for both traits)

This results in a phenotypic ratio of `1:1:1:1`.

5. **Conclusion**: The ratio of `1:1:1:1` indicates that the F1 hybrid is heterozygous for both traits and can produce four different types of gametes. Therefore, the correct answer to the question is that the F1 hybrid produces four different gametes.

### Final Answer:
The correct option is **Option 1: F1 hybrid produces 4 different gametes**.