**Core Concept**
Pancreatitis is an inflammatory condition of the pancreas, which can be acute or chronic. The medical treatment of pancreatitis aims to manage the underlying cause, alleviate symptoms, and prevent complications. This involves a combination of pharmacological interventions and supportive care.

**Why the Correct Answer is Right**
One of the mainstay treatments for pancreatitis is the administration of **octreotide** (a synthetic analogue of somatostatin) to reduce pancreatic secretions and alleviate pain. This is achieved by inhibiting the release of **vasoactive intestinal peptide (VIP)** and **secretin**, which stimulate pancreatic enzyme secretion. Additionally, **proton pump inhibitors (PPIs)** like omeprazole are often prescribed to prevent **stress-induced gastritis**, a common complication of pancreatitis.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because **glucagon** has a pro-inflammatory effect on the pancreas and can worsen pancreatitis. It is not typically used in the treatment of pancreatitis.

**Option B:** This option is incorrect because **vasopressin** can cause vasoconstriction, which may worsen pancreatic ischemia and exacerbate pancreatitis.

**Option C:** This option is incorrect because **metoclopramide** is a prokinetic agent that can stimulate gastric emptying and worsen symptoms of pancreatitis.

**Clinical Pearl / High-Yield Fact**
When managing pancreatitis, it is essential to remember that the **Cullen sign** (periumbilical ecchymosis) and **Grey-Turner sign** (flank ecchymosis) are indicative of severe pancreatitis, requiring immediate medical attention.

**Correct Answer: C. Octreotide.**