Which of the following has non-myelinated nerve fibre

Options

A. Cranial nerves
B. Autonomic nerves
C. Optic nerves
D. Spinal nerves .

Answer

### Step-by-Step Solution:

1. **Understanding Nerve Fibers**:
- Nerve fibers can be classified into myelinated and non-myelinated fibers. Myelinated fibers have a myelin sheath, which is a fatty layer that insulates the axon and facilitates faster nerve impulse conduction.

2. **Identifying Myelinated Nerves**:
- Cranial nerves, spinal nerves, and optic nerves are examples of nerves that typically contain myelinated fibers. The myelin sheath allows for saltatory conduction, which speeds up the transmission of nerve impulses.

3. **Analyzing the Options**:
- **Cranial Nerves**: These are primarily myelinated.
- **Optic Nerves**: As a type of cranial nerve, they also contain myelinated fibers.
- **Spinal Nerves**: These are also known to have myelinated fibers.
- **Autonomic Nerves**: These nerves are characterized by the absence of a myelin sheath, making them non-myelinated.

4. **Conclusion**:
- Since cranial nerves, optic nerves, and spinal nerves all contain myelinated fibers, the only option that has non-myelinated nerve fibers is **autonomic nerves**.

### Final Answer:
The correct answer is **autonomic nerves**.

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