Which condition is heterzygous?

Options

A. TT
B. Tt
C. tt
D. All the above

Answer

To determine which condition is heterozygous from the given options, we need to understand the definitions of homozygous and heterozygous.

### Step-by-Step Solution:

1. **Understand the Terms**:
- **Homozygous**: This condition occurs when an individual has two identical alleles for a particular gene (e.g., TT or tt).
- **Heterozygous**: This condition occurs when an individual has two different alleles for a particular gene (e.g., Tt).

2. **Analyze the Given Options**:
- **Option A**: Capital T, Capital T (TT) - This is homozygous dominant.
- **Option B**: Capital T, small t (Tt) - This is heterozygous.
- **Option C**: Small t, small t (tt) - This is homozygous recessive.
- **Option D**: All of the above - This cannot be correct since only one option is heterozygous.

3. **Identify the Heterozygous Condition**:
- From the analysis, we see that only **Option B (Capital T, small t)** represents a heterozygous condition.

4. **Conclusion**:
- The correct answer is **Option B: Capital T, small t**.