Two exarch vascular bundles occur in

Options

A. monocot root
B. dicot root
C. monocot stem
D. dicot stem.

Answer

To determine where two exarch vascular bundles occur, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definition of Exarch Vascular Bundles**:
- Exarch vascular bundles are characterized by the protoxylem (the earliest formed xylem) being located on the outer side of the vascular bundle.

2. **Differentiate Between Exarch and Endarch**:
- In contrast, endarch vascular bundles have the protoxylem located on the inner side, closer to the pith. This distinction is crucial for identifying the type of vascular bundles present in different plant parts.

3. **Identify the Types of Roots**:
- Both monocot and dicot roots typically exhibit exarch vascular bundles. This means that in the roots of these plants, the protoxylem is always positioned outward.

4. **Examine the Vascular Bundles in Dicot Roots**:
- Dicot roots can have a varying number of exarch vascular bundles, typically ranging from 2 to 4. This means that it is possible to find a dicot root with exactly two exarch vascular bundles.

5. **Consider Monocot Roots and Stems**:
- Monocot roots also exhibit exarch vascular bundles, but they often have a higher number of vascular bundles (polyarch). However, monocot stems will have endarch vascular bundles, which is not relevant to this question.

6. **Conclusion**:
- Since the question specifically asks about "two exarch vascular bundles," the correct answer is that these occur in the roots of dicots, where you can find either 2 or 4 exarch vascular bundles.

### Final Answer:
Two exarch vascular bundles occur in the roots of dicots.

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