Meiotic division of the secondary oocyte is completed:

Options

A. At the time of copulation
B. After zygote formation
C. At the time of fusion of a sperm with an ovum
D. Prior to ovulation

Answer

**Step-by-Step Solution:**

1. **Understanding Meiosis in Oocytes**:
- Meiosis is a type of cell division that reduces the chromosome number by half, resulting in the formation of gametes (sperm and eggs). In females, this process occurs in the ovaries.

2. **Primary Oocyte to Secondary Oocyte**:
- The process begins with a primary oocyte, which undergoes meiosis I. This division results in the formation of a secondary oocyte and a polar body. At this stage, meiosis I is completed, and the secondary oocyte is formed.

3. **Arrested Development**:
- The secondary oocyte remains in a state of arrested development at metaphase II of meiosis until fertilization occurs. This means that it does not complete meiosis II until it is fertilized by a sperm.

4. **Completion of Meiosis II**:
- The secondary oocyte completes meiosis II only upon fertilization. When a sperm successfully penetrates the secondary oocyte, it triggers the completion of meiosis II, resulting in the formation of an ovum and another polar body.

5. **Identifying the Correct Phase**:
- The question asks when the meiotic division of the secondary oocyte is completed. Based on the above understanding, we conclude that the completion of meiosis II occurs at the time of fusion of the sperm with the ovum.

6. **Final Answer**:
- Therefore, the meiotic division of the secondary oocyte is completed at the time of fusion of sperm with the ovum.