The functional megaspore undergoes

Options

A. 3 meiotic divisions to form mature embryo sac
B. 3 mitotic divisions to form mature embryo sac
C. 2 mitotic divisions to form mature embryo sac
D. 2 meiotic divisions to form mature embryo sac

Answer

To answer the question "The functional megaspore undergoes," we will analyze the process step by step:

### Step-by-Step Solution:

1. **Understanding the Functional Megaspore**:
- The functional megaspore is the product of the meiosis of the megaspore mother cell (megasporangium).
- Out of the four haploid spores produced, only one survives to develop into the embryo sac.

2. **Meiotic Division**:
- The megaspore mother cell undergoes meiosis, resulting in four haploid cells.
- Three of these haploid cells degenerate, leaving one functional megaspore.

3. **First Mitotic Division**:
- The functional megaspore enlarges and undergoes its first mitotic division.
- This division results in two haploid nuclei.

4. **Second Mitotic Division**:
- Each of the two nuclei from the first division undergoes mitosis.
- This results in a total of four haploid nuclei.

5. **Third Mitotic Division**:
- The four haploid nuclei undergo another mitotic division.
- This results in a total of eight haploid nuclei.

6. **Formation of the Mature Embryo Sac**:
- The eight haploid nuclei are organized into a mature embryo sac, which consists of seven cells: one egg cell, two synergids, three antipodal cells, and one central cell with two polar nuclei.

### Final Answer:
The functional megaspore undergoes **three mitotic divisions** to form the mature embryo sac.

---