[A]: The three cells of the egg apparatus are arranged in a triangular fashion.
[R): The degenerating synergid forms the seat for pollen tube discharge in the embryo sac

Options

A. If both A and R are true and R is the correct explanation of A
B. If both A and R are true but R is not the correct explanation of A
C. If A is true and R is false
D. If both A and R are false

Answer

To solve the question regarding the assertion and reason provided, we will analyze both statements step by step.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "the three cells of the egg apparatus are arranged in a triangular fashion."
- In the context of angiosperms, the egg apparatus consists of one egg cell and two synergids. This arrangement is indeed triangular, which facilitates the entry of the pollen tube.

2. **Understanding the Reason**:
- The reason states that "the degenerating synergid forms the seat for pollen tube discharge in the embryo sac."
- While it is true that the synergids play a role in guiding the pollen tube to the egg cell, the statement that they form the "seat" for pollen tube discharge is misleading. The synergids degenerate after fertilization, and their primary role is to assist in the fertilization process rather than serve as a discharge seat.

3. **Evaluating the Truth of Each Statement**:
- Both the assertion and reason are true statements in their own right. However, the reason does not correctly explain the assertion. The triangular arrangement is primarily for facilitating the entry of the male gamete, not because of the synergids degenerating.

4. **Conclusion**:
- Since both the assertion and reason are true, but the reason does not correctly explain the assertion, we conclude that the correct answer is the second option.

### Final Answer:
- The correct option is **Option 2**: Both assertion and reason are true, but reason is not the correct explanation of assertion.