Chromosomal disorders are caused due to absence or excess or abnormal arrangement of one or more chromosomes. Failure of segregation of chromatids during cell division cycle results in the gain or loss of a chromosome, and is called aneuploidy. Failure of cytokinesis after telophase stage of cell division results in an increase in a whole set of chromosomes in an organism and, this is known as polyploidy.
Turner's syndrome is caused due to ............... of one of the X chromosome.

Options

A. Presence
B. Excess
C. Absence
D. Both (a) and (b)

Explanation

**Step-by-Step Solution:**

1. **Understanding Chromosomal Disorders**: Chromosomal disorders occur due to abnormalities in the number or structure of chromosomes. This can include the absence (loss) or excess (gain) of chromosomes.

2. **Defining Aneuploidy and Polyploidy**:
- **Aneuploidy** is the condition where there is an abnormal number of chromosomes due to the failure of chromatids to segregate properly during cell division. This results in either a gain or loss of individual chromosomes.
- **Polyploidy** occurs when there is an increase in the number of complete sets of chromosomes, often due to the failure of cytokinesis after the telophase stage of cell division.

3. **Identifying Turner's Syndrome**: Turner's syndrome is a specific chromosomal disorder that affects females. It is characterized by the absence of one of the X chromosomes.

4. **Conclusion**: Turner's syndrome is caused due to the absence of one of the X chromosomes, leading to a total of 45 chromosomes instead of the typical 46 in humans.

**Final Answer**: Turner's syndrome is caused due to the absence of one of the X chromosomes.

---