Prothallus of fern is

Options

A. Dioecious
B. Monoecious
C. Dioecious and protogynous
D. Protogynous

Answer

### Step-by-Step Solution:

1. **Understanding Prothallus**: The prothallus of a fern is the gametophyte stage of the plant life cycle. It is a small, green, and heart-shaped structure that is free-living and photosynthetic.

2. **Classification of Ferns**: Ferns belong to the group known as Pteridophytes. In this group, the dominant phase is the sporophyte, which is the diploid phase that produces spores.

3. **Sporophyte Generation**: The sporophyte has specialized cells called spore mother cells that undergo meiosis to produce haploid spores. These spores are released into the environment.

4. **Germination of Spores**: When the spores germinate, they develop into a multicellular structure known as the gametophyte, which is referred to as the prothallus.

5. **Structure of Prothallus**: The prothallus is typically small, flat, and can photosynthesize, allowing it to produce its own food.

6. **Reproductive Organs**: The prothallus contains both male and female reproductive organs. The male sex organ is called antheridia, which produces sperm (antherozoids), and the female sex organ is called archegonia, which produces eggs.

7. **Monocious vs. Dioecious**: Since the prothallus has both antheridia and archegonia on the same individual, it is classified as monoecious (or monaceous). This means that both male and female reproductive structures are present in the same organism.

8. **Conclusion**: Therefore, the prothallus of a fern is monoecious, as it contains both male and female reproductive organs.

### Final Answer:
The prothallus of fern is **monoecious**.

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