Coralloids roots of ____have symbiotic association with `N_(2)`- fixing cyanobacteria.

Options

A. Pinus
B. Cedrus
C. Cycas
D. Ginkgo

Explanation

To solve the question regarding which plant has coralloid roots that form a symbiotic association with nitrogen-fixing cyanobacteria, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Term "Coralloid Roots":**
- Coralloid roots are specialized structures found in certain plants that have a unique relationship with nitrogen-fixing organisms.

2. **Identify the Plants Mentioned:**
- The options given are:
- Pinus
- Sidrus
- Cycus
- JNCO

3. **Recall the Characteristics of Cycus:**
- Cycus is a genus of gymnosperms, which are seed-producing plants that do not form flowers. They are known for having coralloid roots.

4. **Recognize the Symbiotic Relationship:**
- In Cycus, the coralloid roots are associated with nitrogen-fixing cyanobacteria, specifically genera like Nostoc and Anabaena. This relationship allows the plant to obtain nitrogen, which is essential for its growth.

5. **Eliminate Other Options:**
- Pinus and Sidrus are also gymnosperms, but they do not have coralloid roots associated with cyanobacteria. JNCO is not a recognized plant group in this context.

6. **Conclude with the Correct Answer:**
- Based on the information, the correct answer to the question is **Cycus**.

### Final Answer:
The coralloid roots of **Cycus** have a symbiotic association with nitrogen-fixing cyanobacteria.

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