**Core Concept**
Acute pancreatitis is a sudden inflammation of the pancreas that can be caused by various factors, including gallstones, alcohol consumption, and certain medications. The pathophysiology of acute pancreatitis involves activation of digestive enzymes within the pancreas, leading to autodigestion and inflammation.

**Why the Correct Answer is Right**
The most common cause of acute pancreatitis is gallstones, specifically cholesterol gallstones. When a gallstone obstructs the common bile duct, it can cause a backup of bile and pancreatic juice into the pancreas, leading to activation of digestive enzymes and inflammation. This is known as biliary pancreatitis. The obstruction can cause a sudden increase in pancreatic secretions, leading to autodigestion and inflammation of the pancreas.

**Why Each Wrong Option is Incorrect**
**Option A:** Alcohol consumption is a common cause of chronic pancreatitis, but it is not the most common cause of acute pancreatitis. While alcohol can cause pancreatitis, it is often associated with chronic inflammation and fibrosis.
**Option B:** High triglyceride levels can cause acute pancreatitis, but it is a less common cause compared to gallstones. Hypertriglyceridemia-induced pancreatitis is often seen in patients with genetic disorders or those taking certain medications.
**Option C:** Certain medications, such as corticosteroids and thiazides, can cause pancreatitis, but they are not the most common cause. Medication-induced pancreatitis is often seen in patients with pre-existing pancreatic disease or those taking high doses of the medication.

**Clinical Pearl / High-Yield Fact**
Remember the "3 Ps" of acute pancreatitis: gallstones (Pigment stones), alcohol (Pancreatitis from Prolonged alcohol use), and hypertriglyceridemia (Pancreatitis from Pancreatitis).

**Correct Answer: D. Gallstones**