Seed plants are all

Options

A. heterosporous
B. dioecious
C. monoecious
D. homosporous.

Explanation

### Step-by-Step Solution:

1. **Understanding Seed Plants**: Seed plants are a group of plants that reproduce through seeds. They are primarily divided into two categories: Gymnosperms and Angiosperms.

2. **Reproduction in Seed Plants**: Seed formation is a result of sexual reproduction. This involves the fusion of male and female gametes.

3. **Types of Gametes**: In seed plants, there are two types of gametes:
- **Male Gametes**: These are produced from microspores. Microspores develop into pollen grains, which carry the male gametes.
- **Female Gametes**: These are produced from megaspores. Megaspores develop into ovules, which contain the female gametes.

4. **Heterospory**: Seed plants exhibit a condition known as heterospory, where two different types of spores (microspores and megaspores) are produced. This is crucial for the formation of seeds.

5. **Fertilization**: Once the male and female gametes fuse, fertilization occurs, leading to the formation of a zygote, which eventually develops into a seed.

6. **Development of New Plants**: The seed, once matured, can germinate and grow into a new plant, completing the life cycle of seed plants.

### Summary:
Seed plants are all those plants that reproduce through seeds, which are formed as a result of sexual reproduction involving the fusion of male (microspores) and female (megaspores) gametes. They can be categorized into Gymnosperms and Angiosperms.

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