**Core Concept**
Guillain-Barré Syndrome (GBS) is an autoimmune disorder characterized by rapid-onset muscle weakness and paralysis, often triggered by a preceding infection. It is a type of acute inflammatory demyelinating polyneuropathy (AIDP) that affects the peripheral nerves.

**Why the Correct Answer is Right**
In GBS, the immune system mistakenly attacks the myelin sheath surrounding the peripheral nerves, leading to demyelination and disruption of nerve conduction. This results in muscle weakness and paralysis, which can progress to involve multiple muscle groups. The absence of cells, slightly elevated protein, and normal sugar levels in the cerebrospinal fluid (CSF) are characteristic of GBS. The treatment of choice for GBS is intravenous immunoglobulin (IVIG) or plasmapheresis, which aims to reduce the immune system's attack on the peripheral nerves.

**Why Each Wrong Option is Incorrect**
**Option A:** Corticosteroids are not the primary treatment for GBS, as they may not be effective in reducing the immune system's attack on the peripheral nerves.
**Option B:** Antiviral medications are not indicated in GBS, as the condition is not caused by a viral infection.
**Option C:** Muscle relaxants may be used to manage muscle spasms, but they are not the primary treatment for GBS.

**Clinical Pearl / High-Yield Fact**
GBS is a medical emergency that requires prompt recognition and treatment. The Fisher syndrome variant of GBS is characterized by ophthalmoplegia, ataxia, and areflexia, and is often associated with a worse prognosis.

**Correct Answer:** C.