**Core Concept**
Charcot's triad is a classic clinical presentation of ascending cholangitis, a serious infection of the bile duct. It consists of three key symptoms that are indicative of this condition. The triad was first described by Jean-Martin Charcot in the 19th century.

**Why the Correct Answer is Right**
Charcot's triad is characterized by the combination of fever, right upper quadrant abdominal pain (referred to as "pain" in the options), and jaundice. These symptoms occur due to the inflammation of the bile duct, which leads to an increase in the production of bilirubin, resulting in jaundice, and causes pain due to the stretching and inflammation of the bile duct. The fever is a response to the bacterial infection that causes ascending cholangitis.

**Why Each Wrong Option is Incorrect**
**Option B:** Vomiting is not a part of Charcot's triad, although it may occur in some cases of ascending cholangitis due to the associated inflammation and infection.
**Option C:** Abdominal distension is not a specific component of Charcot's triad, and while it may be present in some cases of ascending cholangitis, it is not a defining characteristic.
**Option D:** Chills are a nonspecific symptom that may occur in various infections, but they are not a part of Charcot's triad.

**Clinical Pearl / High-Yield Fact**
It is essential to recognize Charcot's triad in a timely manner, as ascending cholangitis can progress rapidly and lead to serious complications, including sepsis and even death. Prompt diagnosis and treatment with antibiotics and biliary drainage can significantly improve outcomes.

**✓ Correct Answer: A. Fever, pain, jaundice**