**Core Concept**
The diagnosis and management of acute exacerbation of ulcerative colitis (UC) involve understanding the pathophysiology of the condition and the goals of treatment. Ulcerative colitis is a type of inflammatory bowel disease characterized by chronic inflammation and ulceration of the colonic mucosa, leading to symptoms such as diarrhea, abdominal pain, and weight loss. The primary goal of treatment is to induce and maintain remission, control symptoms, and prevent complications.

**Why the Correct Answer is Right**
In the management of acute exacerbation of UC, the initial step is to initiate corticosteroids, such as **methylprednisolone**, to reduce inflammation and induce remission. Corticosteroids act by inhibiting the release of pro-inflammatory cytokines, such as **TNF-alpha** and **IL-1 beta**, which play a key role in the pathogenesis of UC. This leads to a decrease in inflammation and an improvement in symptoms. Corticosteroids are most effective when used in the early stages of an acute exacerbation, as they can prevent further complications and reduce the risk of colectomy.

**Why Each Wrong Option is Incorrect**
**Option A:** Aminosalicylates, such as **sulfasalazine**, are used as maintenance therapy to prevent relapse in patients with UC, but they are not the first-line treatment for acute exacerbation.
**Option B:** Immunomodulators, such as **azathioprine**, are used to maintain remission in patients with UC, but they have a slower onset of action and are not suitable for acute exacerbation.
**Option C:** Biologics, such as **infliximab**, are used to treat moderate to severe UC, but they are not typically used as the first-line treatment for acute exacerbation.

**Clinical Pearl / High-Yield Fact**
In the management of UC, it is essential to identify and treat complications promptly, such as **toxic megacolon**, which can be a medical emergency.

**Correct Answer:** C. Methylprednisolone.