An abnormal human baby with `XXX` sex chromosomes was born due to

Options

A. formation of abnormal ova in the mother
B. fusion of two ova and one sperm
C. fusion of two sperms and one ovum
D. formation of abnormal sperms in the father

Explanation

### Step-by-Step Solution:

1. **Understanding the Chromosomal Makeup**:
- The question states that an abnormal human baby has `XXX` sex chromosomes. This indicates that the baby is genetically female, as females typically have two X chromosomes (XX), and the presence of an additional X chromosome leads to the condition known as Triple X syndrome (XXX syndrome).

2. **Identifying the Cause of the Condition**:
- The abnormality in the sex chromosomes can arise from errors during the formation of gametes (ova and sperm) in the parents. Specifically, we need to consider how the extra X chromosome could have been produced.

3. **Meiosis and Gamete Formation**:
- Meiosis is the process by which gametes are formed. In females, meiosis involves two rounds of cell division (meiosis I and meiosis II) that reduce the chromosome number by half. Errors during these divisions can lead to gametes with an abnormal number of chromosomes.

4. **Analyzing Possible Causes**:
- The options provided include:
- Formation of abnormal ova in the mother
- Fusion of two ova and one sperm
- Fusion of two sperms and one ovum
- Formation of abnormal sperm in the father
- The most relevant option is the formation of abnormal ova in the mother, where the ova could end up with an extra X chromosome due to nondisjunction during meiosis.

5. **Conclusion**:
- The correct answer is that the abnormal human baby with `XXX` sex chromosomes was born due to the **formation of abnormal ova in the mother**. This results in the fertilization of an abnormal ovum with a normal sperm, leading to the presence of three X chromosomes in the offspring.