**Core Concept**
Primary biliary cirrhosis (PBC) is a chronic autoimmune liver disease characterized by progressive destruction of intrahepatic bile ducts, leading to cholestasis and cirrhosis. The condition is often associated with the presence of antimitochondrial antibodies (AMA).

**Why the Correct Answer is Right**
The most common symptom of primary biliary cirrhosis is pruritus (itching), which is thought to result from the accumulation of bile salts in the skin due to impaired bile flow. Pruritus is often the initial symptom and can be severe, affecting the patient's quality of life. The pathophysiology involves the impaired excretion of bile salts, leading to their accumulation in the bloodstream and subsequent deposition in the skin, causing itching.

**Why Each Wrong Option is Incorrect**
* **Option A:** Fatigue is a common symptom of cirrhosis, but it is not the most specific or sensitive symptom of primary biliary cirrhosis.
* **Option B:** Jaundice can occur in PBC, but it is not the most common presenting symptom.
* **Option C:** Weight loss is a nonspecific symptom that can occur in various liver diseases, including PBC, but it is not the most characteristic symptom of this condition.

**Clinical Pearl / High-Yield Fact**
The presence of antimitochondrial antibodies (AMA) is a diagnostic hallmark of primary biliary cirrhosis, with a sensitivity of up to 95%. A positive AMA test can support the diagnosis of PBC, especially in the absence of other liver diseases.

**Correct Answer:** B. Jaundice.