## Core Concept
The Passaro triangle, also known as the gastrinoma triangle, is an anatomical region used to localize gastrinomas, which are tumors that produce excessive amounts of gastrin, leading to Zollinger-Ellison syndrome. This triangle is defined by specific landmarks in the abdomen.

## Why the Correct Answer is Right
The Passaro triangle is specifically defined by the following boundaries:
- The junction of the second and third parts of the duodenum (superiorly)
- The junction of the neck and body of the pancreas (inferiorly)
- The common bile duct (medially)

## Why Each Wrong Option is Incorrect
- **Option A:** The junction of the second and third parts of the duodenum is indeed a boundary of the Passaro triangle, making it a correct component.
- **Option B:** The junction of the neck and body of the pancreas serves as an inferior boundary, which is also correct.
- **Option D:** The common bile duct forms the medial boundary, which is accurate.

## Why Option C is Incorrect
- **Option C:** This option would represent an incorrect boundary since the Passaro triangle is defined by the above-mentioned structures, and any option not including these would be incorrect.

## Clinical Pearl / High-Yield Fact
A key clinical pearl is that gastrinomas are often found within the Passaro triangle, and identifying this triangle is crucial for surgeons and gastroenterologists managing patients with Zollinger-Ellison syndrome.

## Correct Answer Line
**Correct Answer: C.**