Which one of the following is a correct statement ?

Options

A. Dominant trait can be expressed in homozygous condition only
B. Recessive condition is expressed in homozygous condition only
C. Dominant condition cannot be expressed in homozygous condition
D. All of the above

Answer

To solve the question "Which one of the following is a correct statement?" we need to analyze each option provided in the question based on our understanding of genetics, specifically dominant and recessive traits.

### Step-by-Step Solution:

1. **Understanding Dominant and Recessive Traits**:
- Dominant traits are expressed when at least one dominant allele is present. They can be expressed in both homozygous (two dominant alleles) and heterozygous (one dominant and one recessive allele) conditions.
- Recessive traits are only expressed when two recessive alleles are present (homozygous condition). In the presence of a dominant allele, the recessive trait is masked.

2. **Evaluating Option A**:
- **Statement**: "A dominant trait can be expressed in homozygous condition only."
- **Analysis**: This statement is incorrect because a dominant trait can also be expressed in a heterozygous condition. Therefore, this option is false.

3. **Evaluating Option B**:
- **Statement**: "Recessive condition is expressed in homozygous condition only."
- **Analysis**: This statement is correct. A recessive trait can only be expressed when both alleles are recessive (homozygous condition). Hence, this option is true.

4. **Evaluating Option C**:
- **Statement**: "Dominant condition cannot be expressed in homozygous condition."
- **Analysis**: This statement is incorrect. A dominant trait can be expressed in both homozygous and heterozygous conditions. Therefore, this option is false.

5. **Evaluating Option D**:
- **Statement**: "All of the above."
- **Analysis**: Since options A and C are incorrect, this option is also false.

6. **Conclusion**:
- The only correct statement among the options is **Option B**: "Recessive condition is expressed in homozygous condition only."

### Final Answer:
**B. Recessive condition is expressed in homozygous condition only.**

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