In embryo sac double fertilization means:
I. Formation of double zygote.
II. Fusion between egg and male gamete
III. Formation of perisperm.
IV. Fusion between secondary nucleus and male gamete.

Options

A. I and II are correct
B. II and III are correct
C. II and IV are correct
D. III and IV are correct

Answer

To answer the question about double fertilization in the embryo sac, let's analyze each of the given statements step by step.

### Step-by-Step Solution:

1. **Understanding Double Fertilization**:
- In flowering plants (angiosperms), double fertilization is a unique process where one male gamete fuses with the egg cell and another male gamete fuses with the polar nuclei in the central cell of the embryo sac.

2. **Analyzing Statement I**:
- **Statement**: Formation of double zygote.
- **Evaluation**: This statement is incorrect. In double fertilization, only one zygote is formed when one male gamete fuses with the egg cell.

3. **Analyzing Statement II**:
- **Statement**: Fusion between egg and male gamete.
- **Evaluation**: This statement is correct. One male gamete fuses with the egg cell to form the zygote.

4. **Analyzing Statement III**:
- **Statement**: Formation of perisperm.
- **Evaluation**: This statement is incorrect. Double fertilization leads to the formation of endosperm, not perisperm.

5. **Analyzing Statement IV**:
- **Statement**: Fusion between secondary nucleus and male gamete.
- **Evaluation**: This statement is correct. The second male gamete fuses with the secondary nucleus (formed by the fusion of polar nuclei) to form the endosperm.

6. **Conclusion**:
- Based on the evaluations, the correct statements regarding double fertilization are:
- Statement II (Fusion between egg and male gamete) is correct.
- Statement IV (Fusion between secondary nucleus and male gamete) is also correct.
- Therefore, the correct answer is that statements II and IV are correct.

### Final Answer:
The correct statements regarding double fertilization in the embryo sac are II and IV.

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