**Core Concept**
The plasma half-life of insulin is a critical parameter that determines its duration of action and therapeutic efficacy. Insulin is a hormone produced by the pancreas that regulates glucose metabolism in the body.

**Why the Correct Answer is Right**
The plasma half-life of insulin is approximately 4-6 minutes, which is the time it takes for the plasma concentration of insulin to decrease by half. This rapid clearance is due to the insulin-degrading enzyme (IDE) that breaks down insulin in the bloodstream. The short half-life of insulin necessitates frequent administration to maintain its therapeutic effects. The liver is the primary site of insulin degradation, where IDE is present in high concentrations.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as the half-life of insulin is not in the range of minutes to hours, which would be more characteristic of other hormones like growth hormone or cortisol.
**Option B:** This option is incorrect as the half-life of insulin is not significantly influenced by renal function, which is a critical determinant for other drugs like digoxin or vancomycin.
**Option C:** This option is incorrect as the half-life of insulin is not in the range of hours to days, which would be more characteristic of other hormones like thyroid-stimulating hormone (TSH) or adrenocorticotropic hormone (ACTH).

**Clinical Pearl / High-Yield Fact**
The rapid clearance of insulin is a key factor in the development of hypoglycemia, a potentially life-threatening complication of insulin therapy. This highlights the importance of careful dosing and monitoring of blood glucose levels in patients receiving insulin.

**Correct Answer: C. 4-6 minutes**