**Core Concept**
Chronic pancreatitis is a progressive inflammatory disease of the pancreas, characterized by atrophy of the pancreatic acini, fibrosis, and ductal dilatation. The disease results from recurrent episodes of inflammation, leading to irreversible damage and impairment of pancreatic exocrine function.

**Why the Correct Answer is Right**
The most common cause of chronic pancreatitis in adults is alcohol abuse. Prolonged consumption of excessive amounts of alcohol leads to the formation of reactive oxygen species, which damage the pancreatic cells and trigger an inflammatory response. The repeated cycle of inflammation, necrosis, and repair results in fibrosis and atrophy of the pancreatic acini, ultimately impairing pancreatic exocrine function. The patient's symptoms of weight loss, steatorrhea, and malabsorption are consistent with pancreatic insufficiency.

**Why Each Wrong Option is Incorrect**
**Option A:** Cigarette smoking is a risk factor for chronic pancreatitis, but it is not the most common cause. While smoking may contribute to the development of the disease, it is not the primary underlying factor.
**Option B:** Hypertriglyceridemia is a rare cause of acute pancreatitis, but it is not typically associated with chronic pancreatitis. The patient's presentation and biopsy findings do not suggest an acute or recurrent episode of pancreatitis.
**Option C:** Genetic mutations, such as those associated with hereditary pancreatitis, can cause chronic pancreatitis. However, these cases are rare and typically present at a younger age.

**Clinical Pearl / High-Yield Fact**
Chronic pancreatitis is often associated with other systemic diseases, including diabetes mellitus, liver disease, and osteoporosis. A thorough evaluation of the patient's medical history and physical examination is essential to identify these comorbidities.

**Correct Answer: A. Alcohol abuse is the most common cause of chronic pancreatitis in adults.**