**Core Concept**
A mucocele of the gallbladder is a pathological condition characterized by the accumulation of mucin within the gallbladder, often as a result of chronic obstruction, such as that caused by gallstones. This leads to an enlarged and distended gallbladder, which can become palpable.

**Why the Correct Answer is Right**
The correct answer is D, as the gallbladder is indeed never palpable in the case of a mucocele. This is because the distended gallbladder is filled with viscous mucin, which does not allow for normal gallbladder contraction or movement, making it impossible to palpate. The clinical presentation of a mucocele typically includes abdominal pain, jaundice, and weight loss, but palpation of the gallbladder is not a characteristic feature.

**Why Each Wrong Option is Incorrect**
**Option A:** A mucocele of the gallbladder is indeed a complication of gallstones, as the obstruction caused by the stone leads to the accumulation of mucin within the gallbladder.
**Option B:** Early cholecystectomy is the treatment of choice for a mucocele of the gallbladder, as surgical removal of the gallbladder is necessary to prevent further complications.
**Option C:** Obstruction at the neck of the gallbladder is a common cause of a mucocele, as the stone or other obstruction prevents normal bile flow and leads to mucin accumulation.

**Clinical Pearl / High-Yield Fact**
A mucocele of the gallbladder is often associated with a palpable mass in the right upper quadrant, but this is not due to the gallbladder itself being palpable. Instead, the distended gallbladder can cause adjacent structures, such as the liver or colon, to become palpable.

**✓ Correct Answer: D. Gallbladder is never palpable.**