**Core Concept**
A mucocele of the gallbladder is a condition characterized by the accumulation of mucus within the gallbladder, often resulting from an obstruction of the cystic duct. This leads to a distended, filled gallbladder that may mimic other gallbladder pathologies, such as gallstones or gallbladder cancer.

**Why the Correct Answer is Right**
The treatment of choice for a mucocele of the gallbladder involves the surgical removal of the gallbladder, also known as a cholecystectomy. This is because the mucocele is often associated with an underlying obstruction, which cannot be resolved by medical therapy alone. A cholecystectomy is the definitive treatment to prevent further complications, such as gallbladder rupture, peritonitis, or malignant transformation.

**Why Each Wrong Option is Incorrect**
**Option A:** Conservative management with antibiotics may be used in some cases of mucocele, but it is not the treatment of choice for a symptomatic or obstructed mucocele.
**Option B:** Endoscopic retrograde cholangiopancreatography (ERCP) may be used to diagnose or treat the underlying cause of the mucocele, such as a cystic duct obstruction, but it is not a substitute for surgical removal of the gallbladder.
**Option C:** Percutaneous drainage may be used to temporarily relieve symptoms in some cases, but it is not a definitive treatment and may lead to further complications.

**Clinical Pearl / High-Yield Fact**
A mucocele of the gallbladder is often associated with an underlying obstruction, which can be caused by gallstones, tumors, or other pathologies. It is essential to identify and address the underlying cause to prevent recurrence.

**Correct Answer: C. Cholecystectomy. Surgical removal of the gallbladder is the definitive treatment for a mucocele.**