**Core Concept**
Multiple sclerosis (MS) is a chronic autoimmune disease characterized by demyelination of the central nervous system (CNS). Disease-modifying therapies (DMTs) aim to reduce disease activity and prevent relapses.

**Why the Correct Answer is Right**
Interferon beta (IFN-β) is a type of DMT that has been shown to reduce the frequency of relapses in patients with MS. It works by modulating the immune response, reducing the production of pro-inflammatory cytokines, and promoting the release of anti-inflammatory cytokines. IFN-β also has a neuroprotective effect, which helps to preserve CNS function.

**Why Each Wrong Option is Incorrect**
**Option A:** Natalizumab is a DMT that targets the α4-integrin subunit, preventing lymphocytes from crossing the blood-brain barrier. While effective in reducing relapses, it is not the correct answer because it is not an interferon-based therapy.
**Option B:** Glatiramer acetate is an immunomodulator that modulates the immune response, but it is not an interferon-based therapy and has a different mechanism of action.
**Option C:** Fingolimod is a sphingosine 1-phosphate receptor modulator that reduces lymphocyte egress from lymphoid tissues. It is an effective DMT, but it is not an interferon-based therapy.

**Clinical Pearl / High-Yield Fact**
When selecting a DMT for a patient with MS, consider the patient's disease activity, comorbidities, and previous treatment history. Interferon-based therapies like IFN-β are often a good choice for patients with relapsing-remitting MS, but individualize treatment based on patient-specific factors.

**Correct Answer:** C. Interferon beta (IFN-β) is given to prevent relapse in multiple sclerosis.