## Core Concept
Insulinoma is a type of pancreatic tumor that produces excess insulin, leading to hypoglycemia. It is typically a benign tumor and is often associated with specific clinical and laboratory findings.

## Why the Correct Answer is Right
To determine why the correct answer is right, we need to evaluate each option based on known characteristics of insulinoma.

## Why Each Wrong Option is Incorrect
- **Option A:** Typically, insulinomas are small, solitary tumors usually found in the pancreas. They are often benign.
- **Option B:** Symptoms of insulinoma can include confusion, dizziness, tremors, and palpitations due to hypoglycemia.
- **Option C:** Insulinomas secrete insulin inappropriately, even when glucose levels are low, leading to hypoglycemia.
- **Option D:** This option's accuracy depends on the specifics of the statement, which are not provided.

## Clinical Pearl / High-Yield Fact
A key clinical pearl for insulinoma is the "Whipple's triad," which consists of:
1. Symptoms known or likely to be caused by hypoglycemia especially after fasting or heavy exercise.
2. A low plasma glucose measured at the time of the symptoms.
3. Relief of symptoms when the glucose is raised to normal.

## Correct Answer: D.