**The Outermost Covering of the Nerve**

The outermost covering of the nerve is called the **Epineurium**. It is a thick layer of connective tissue that encloses the entire nerve and provides protection and support to the nerve fibers within.

**Function of Epineurium:**

1. **Protection:** The epineurium acts as a protective layer for the delicate nerve fibers. It shields the nerve from external forces and prevents damage.

2. **Support:** The epineurium provides structural support to the nerve. It helps to maintain the shape and integrity of the nerve and prevents it from collapsing.

3. **Containment:** The epineurium keeps the nerve fibers within the nerve bundle together. It holds the nerve fibers in place and prevents them from separating or getting tangled.

4. **Flexibility:** The epineurium allows the nerve to bend and move without causing damage to the underlying nerve fibers. It provides flexibility to the nerve, allowing it to withstand stretching and compression.

**Comparison with Other Nerve Coverings:**

- **Perineurium:** The perineurium is a layer of connective tissue that surrounds individual fascicles within a nerve bundle. It provides protection and support to the fascicles and contains blood vessels that supply nutrients to the nerve fibers.

- **Myelin Sheath:** The myelin sheath is a layer of fatty material that surrounds and insulates the nerve fibers. It speeds up the conduction of nerve impulses and provides electrical insulation to prevent the loss of nerve signals.

- **Capsule:** The term "capsule" is not specifically used to describe the outer covering of a nerve. However, in certain contexts, it can refer to a protective structure that surrounds a nerve or an organ. For example, the joint capsule encloses and protects the joint, while the renal capsule surrounds and protects the kidneys.

So, the correct answer is option B: Epineurium.