There is dominant (G) over black (g). Which of the following will most probabily give `50%` black and `50%` grey offspring ?

Options

A. `GG xxgg`
B. `Ggxxgg`
C. `GGxxGg`
D. `ggxxgg`

Answer

To solve the problem of determining which cross will most likely yield 50% black (heterozygous Gg) and 50% grey (homozygous gg) offspring, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Genotypes**:
- The dominant allele is represented by "G" (grey), and the recessive allele is represented by "g" (black).
- The possible genotypes are:
- Homozygous dominant: GG (grey)
- Heterozygous: Gg (grey)
- Homozygous recessive: gg (black)

2. **Identify the Offspring Requirements**:
- We want to achieve a ratio of 50% black (gg) and 50% grey (Gg).
- This means we need to cross a heterozygous genotype (Gg) with a homozygous recessive genotype (gg).

3. **Analyze the Options**:
- **Option A**: GG x gg
- Offspring: 100% Gg (grey)
- **Option B**: Gg x gg
- Offspring: 50% Gg (grey) and 50% gg (black)
- **Option C**: GG x Gg
- Offspring: 50% GG (grey) and 50% Gg (grey)
- **Option D**: gg x gg
- Offspring: 100% gg (black)

4. **Determine the Correct Cross**:
- From the analysis, only **Option B (Gg x gg)** produces the desired ratio of 50% black (gg) and 50% grey (Gg) offspring.

5. **Conclusion**:
- The correct answer is **Option B: Gg x gg**.