The mature seeds of plants such as gram and peas, possess no endosperm, because :

Options

A. these plants are not angiosperms
B. there is no fertilization in them
C. endosperm is not formed in them
D. endosperm gets used by the developing embryo during seed development

Explanation

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks why mature seeds of plants like gram and peas do not possess endosperm. Endosperm is a tissue that provides nutrition to the developing embryo in seeds.

2. **Identifying the Type of Plants**: Gram and peas are both classified as angiosperms, which are flowering plants. This means they undergo a process of fertilization that leads to seed formation.

3. **Analyzing the Options**:
- **Option A**: "These plants are not angiosperms" - This is incorrect because both gram and peas are indeed angiosperms.
- **Option B**: "There is no fertilization in them" - This is also incorrect because fertilization is essential for the development of seeds.
- **Option C**: "Angiosperm is not formed in them" - This statement is misleading. While angiosperm is formed, it is utilized during seed development.
- **Option D**: "Angiosperm gets used by the developing embryo during seed development" - This is the correct option. In certain seeds, like those of gram and peas, the endosperm is consumed by the developing embryo, leading to the absence of endosperm in the mature seed.

4. **Conclusion**: The correct answer is that the endosperm is utilized by the developing embryo during seed development, which is why mature seeds of gram and peas do not possess endosperm.