**Core Concept**
Multiple Sclerosis (MS) is a chronic autoimmune disease characterized by demyelination of the central nervous system (CNS), leading to neurological deficits. The disease process involves an immune-mediated attack on the myelin sheath surrounding nerve fibers, resulting in impaired nerve conduction and clinical manifestations.

**Why the Correct Answer is Right**
The most common presentation of MS is an acute monoocular optic neuritis, which is often the initial symptom of the disease. This occurs due to inflammation and demyelination within the optic nerve, leading to visual loss, pain on eye movement, and decreased color vision. The optic nerve is particularly susceptible to demyelination due to its long length and relatively poor blood supply. The presence of oligoclonal bands in the cerebrospinal fluid (CSF) and abnormal visual evoked potentials (VEPs) support the diagnosis of optic neuritis.

**Why Each Wrong Option is Incorrect**
**Option A:** While sensory symptoms, such as numbness or tingling, can occur in MS, they are not the most common initial presentation. Sensory symptoms often occur in conjunction with other symptoms, such as weakness or visual disturbances.
**Option B:** Motor symptoms, such as weakness or paralysis, can occur in MS, but they are not the most common initial presentation. Motor symptoms often occur in more advanced stages of the disease.
**Option C:** Cognitive symptoms, such as memory or attention deficits, can occur in MS, but they are not the most common initial presentation. Cognitive symptoms often occur in later stages of the disease or in association with other symptoms.

**Clinical Pearl / High-Yield Fact**
The McDonald criteria, established in 2017, provide a standardized approach to diagnosing MS, emphasizing the presence of at least one clinical presentation (such as optic neuritis) and two or more supporting features (such as oligoclonal bands in the CSF or abnormal VEPs).

**Correct Answer: C. Motor symptoms, such as weakness or paralysis, can occur in MS, but they are not the most common initial presentation. Motor symptoms often occur in more advanced stages of the disease.**