Mycorrhiza is a mutualistic association of plants root with fungi. The association occurs in

Options

A. 83% dicots
B. 79% monocots
C. nearly all gymnosperm
D. all of these

Answer

### Step-by-Step Solution:

1. **Understanding Mycorrhiza**: Mycorrhiza refers to the mutualistic association between plant roots and fungi. In this relationship, both organisms benefit from each other.

2. **Role of Fungi**: Fungi are heterotrophic organisms, meaning they cannot produce their own food. They rely on other sources for nutrients. In the mycorrhizal association, fungi provide shelter and essential nutrients to the plants.

3. **Role of Plants**: In return, plants benefit from the fungi as they assist in water uptake and provide protection. Fungi also help in the absorption of minerals from the soil, which are crucial for plant growth.

4. **Occurrence of Mycorrhiza**: This mutualistic association is widespread and can be found in almost all types of plants. Research indicates that approximately 83% of dicots and 79% of monocots form mycorrhizal associations. Additionally, nearly all gymnosperms also have mycorrhizal relationships.

5. **Conclusion**: Based on the information provided, mycorrhiza occurs in a variety of plants, including dicots, monocots, and gymnosperms. Therefore, the correct answer to the question is that mycorrhiza is present in all of these types of plants.

### Final Answer:
Mycorrhiza is a mutualistic association that occurs in almost all plants, including dicots, monocots, and gymnosperms.