**Core Concept**
Creatinine clearance is a measure of kidney function, calculated as the volume of blood plasma that is cleared of creatinine per unit time. It is an important indicator of glomerular filtration rate (GFR), which declines with age and kidney disease.

**Why the Correct Answer is Right**
The Cockcroft-Gault equation is commonly used to estimate creatinine clearance (CrCl) in adults: CrCl = (140 - age) * (weight in kg) / (72 * plasma creatinine in mg/dL) for men, adjusted for body surface area. Given the patient's age (60 years), weight (60 kg), and plasma creatinine (3 mg/dL), we can plug these values into the equation to calculate CrCl.

**Why Each Wrong Option is Incorrect**
**Option A:** This option would be incorrect because it doesn't take into account the patient's age and weight.
**Option B:** This option might seem plausible, but it doesn't use the correct formula or units for creatinine clearance.
**Option C:** This option is incorrect because it doesn't adjust for the patient's body surface area.

**Clinical Pearl / High-Yield Fact**
The Cockcroft-Gault equation is a useful tool for estimating creatinine clearance in patients with kidney disease, but it should be used with caution in patients with body surface area > 1.73 m^2.

**Correct Answer:** C. 18 mL/min.