Which group of nerve fibre is least susceptible to hypoxia?

**Core Concept**
The underlying principle being tested is the susceptibility of different nerve fiber groups to hypoxia, which is related to their **metabolic rates** and **energy requirements**. Nerve fibers are classified based on their diameter and myelination, which influence their conduction velocity and metabolic demands.

**Why the Correct Answer is Right**
Since the correct answer is not provided, let's discuss the general principle: larger, myelinated fibers (such as A fibers) have higher metabolic rates and are more susceptible to hypoxia compared to smaller, unmyelinated fibers (such as C fibers).

**Why Each Wrong Option is Incorrect**
**Option A:** Would be incorrect if it represented a larger, myelinated fiber type, as these are more susceptible to hypoxia due to higher metabolic demands.
**Option B:** Similarly, if representing a fiber type with high energy requirements, it would be incorrect.
**Option D:** If this option represented a fiber type known to be highly sensitive to lack of oxygen, it would also be an incorrect choice.

**Clinical Pearl / High-Yield Fact**
Remember that **C fibers**, which are small and unmyelinated, are generally more resistant to hypoxia than larger, myelinated **A fibers**. This is crucial in understanding the clinical presentation of hypoxic injuries to the nervous system.

**Correct Answer:** Correct Answer: C. C fibers.