**Core Concept**
The question is testing the ability to identify drugs that cause significant nephrotoxicity, a well-documented side effect of certain medications. Nephrotoxicity refers to the potential of a drug to damage the kidneys, either by direct or indirect mechanisms, leading to impaired renal function.

**Why the Correct Answer is Right**
Aminoglycoside antibiotics, such as gentamicin, are known to cause nephrotoxicity by inhibiting protein synthesis in renal cells, leading to acute kidney injury. This is due to the binding of aminoglycosides to the 30S ribosomal subunit, disrupting normal protein synthesis. The resulting damage to the renal tubules can lead to increased serum creatinine levels and decreased glomerular filtration rate.

**Why Each Wrong Option is Incorrect**
**Option A:** Cephalosporins are a class of beta-lactam antibiotics that are generally well-tolerated and not associated with significant nephrotoxicity.

**Option B:** Metronidazole is an antibiotic and antiprotozoal medication that is not commonly associated with nephrotoxicity.

**Option C:** Vancomycin is a glycopeptide antibiotic that can cause nephrotoxicity, but it is less common compared to aminoglycosides.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that aminoglycoside antibiotics should be used judiciously, with careful monitoring of renal function, especially in patients with pre-existing kidney disease.

**Correct Answer:** C. Vancomycin