Development of embryo sac from a single functional megaspore is termed as:

Options

A. Disporic development
B. Monosporic development
C. Trisporic development
D. Quadsporic development

Explanation

To solve the question regarding the development of the embryo sac from a single functional megaspore, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Terms**: The question refers to the development of the embryo sac, which is a crucial part of the female gametophyte in flowering plants. The embryo sac develops from a megaspore.

2. **Identifying the Megaspore**: In flowering plants, typically four megaspores are formed through meiosis, but usually, only one of these megaspores is functional. The remaining three degenerate.

3. **Defining the Development Type**: The process of development from a single functional megaspore is specifically termed as "monosporic development". The prefix "mono-" indicates one, which aligns with the fact that only one megaspore contributes to the formation of the embryo sac.

4. **Evaluating the Options**:
- **Diasporic Development**: This term does not relate to the development of the embryo sac from a megaspore.
- **Monosporic Development**: This is the correct term, as it refers to the development from one functional megaspore.
- **Tri-sporic Development**: This term would imply the involvement of three megaspores, which is not the case here.
- **Quad-sporic Development**: This would imply the involvement of all four megaspores, which is also incorrect.

5. **Conclusion**: Based on the definitions and the understanding of the process, the correct answer to the question is "monosporic development".

### Final Answer:
The development of the embryo sac from a single functional megaspore is termed as **monosporic development**.

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