**Question:** The ratio of c peptide: insulin in normal adults is

A. 1:1
B. 2:1
C. 3:1
D. 4:1

**Core Concept:** C-peptide and insulin are co-secreted by the beta cells of the pancreas in a 1:1 ratio during normal insulin secretion.

**Why the Correct Answer is Right:** C-peptide is a byproduct of insulin synthesis, and both are co-secreted by the beta cells in pancreatic islets. Under normal physiological conditions, the secretion of C-peptide is equivalent to that of insulin.

**Why Each Wrong Option is Incorrect:**

A. 1:1 (Correct)
B. 2:1 - The ratio is not twice as high as C-peptide, which is incorrect.
C. 3:1 - This ratio is too high, not close to the correct 1:1 ratio.
D. 4:1 - This ratio is also too high and does not match the correct 1:1 ratio.

**Clinical Pearl / High-Yield Fact:** C-peptide measurement can provide valuable information in diagnosing pancreatic beta cell dysfunction, such as in type 1 diabetes mellitus, where C-peptide levels decrease before insulin levels.

**Correct Answer:** A. 1:1