**Core Concept**
Enalapril, an angiotensin-converting enzyme (ACE) inhibitor, is a prodrug that requires conversion to its active form, enalaprilat, in the kidneys. This conversion is essential for its therapeutic effect. However, in patients with chronic renal failure, the reduced renal function impairs the conversion of enalapril to enalaprilat.

**Why the Correct Answer is Right**
The correct administration of enalapril in patients with chronic renal failure requires careful consideration of its pharmacokinetics. Since enalapril is a prodrug, its bioavailability and efficacy depend on its conversion to enalaprilat in the kidneys. In patients with reduced renal function, the conversion of enalapril to enalaprilat is impaired, leading to reduced efficacy. To overcome this, enalapril should be administered in divided doses, ideally at the end of the dialysis session, when the patient's renal function is closest to normal.

**Why Each Wrong Option is Incorrect**
**Option A:** Administering enalapril with meals can lead to variable absorption and reduced bioavailability, making it less effective in patients with chronic renal failure.
**Option B:** Administering enalapril at the beginning of the dialysis session may not allow for optimal conversion to enalaprilat, as the patient's renal function may still be impaired.
**Option D:** Administering enalapril without considering the patient's renal function may lead to inadequate conversion to enalaprilat, reducing the medication's efficacy.

**Clinical Pearl / High-Yield Fact**
The timing of enalapril administration in patients with chronic renal failure is crucial, as it affects the conversion to its active form, enalaprilat. Administering enalapril at the end of the dialysis session can help optimize its efficacy.

**Correct Answer:** C.