Which of the following has normal sex chromosome complements.

Options

A. Down's syndrome
B. Klinefelter's syndrome
C. Super female
D. Turner's syndrome

Answer

To determine which of the following has a normal sex chromosome complement, we need to analyze each option provided in the context of genetic conditions related to sex chromosomes.

### Step-by-Step Solution:

1. **Understand Turner Syndrome**:
- Turner syndrome is characterized by the presence of a single X chromosome (X0), resulting in a total of 45 chromosomes. This condition affects females and indicates an abnormal sex chromosome complement.
- **Conclusion**: Turner syndrome does not have a normal sex chromosome complement.

2. **Understand Super Female (Triple X Syndrome)**:
- Triple X syndrome is characterized by the presence of three X chromosomes (XXX), resulting in a total of 47 chromosomes. This condition also indicates an abnormal sex chromosome complement.
- **Conclusion**: Super Female does not have a normal sex chromosome complement.

3. **Understand Klinefelter Syndrome**:
- Klinefelter syndrome is characterized by the presence of an extra X chromosome (XXY), resulting in a total of 47 chromosomes. This condition affects males and indicates an abnormal sex chromosome complement.
- **Conclusion**: Klinefelter syndrome does not have a normal sex chromosome complement.

4. **Understand Down Syndrome**:
- Down syndrome is caused by trisomy of the 21st chromosome, which affects the autosomes. Individuals with Down syndrome typically have a normal sex chromosome complement, which can be either XX (female) or XY (male).
- **Conclusion**: Down syndrome has a normal sex chromosome complement.

### Final Answer:
Among the conditions analyzed, **Down syndrome** is the only one that has a normal sex chromosome complement.

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