**Core Concept**
Ototoxicity refers to the toxic effect of a substance on the ear, particularly the cochlea or auditory nerve, leading to hearing loss or tinnitus. Nephrotoxicity is the toxic effect of a substance on the kidneys, causing damage to renal tissue and impairing their function. Certain medications can cause both ototoxicity and nephrotoxicity due to their mechanism of action or metabolic byproducts.

**Why the Correct Answer is Right**
Aminoglycoside antibiotics, such as gentamicin and tobramycin, are known to cause ototoxicity and nephrotoxicity. This is due to their ability to bind to calcium ions in the inner ear and renal tissue, leading to damage and dysfunction. The mechanism of ototoxicity involves the inhibition of mitochondrial protein synthesis, while nephrotoxicity is thought to result from the formation of reactive oxygen species and the activation of inflammatory pathways.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because ampicillin, a penicillin antibiotic, is not typically associated with ototoxicity or nephrotoxicity.

**Option B:** This option is incorrect because metronidazole, an antibiotic and antiprotozoal medication, primarily causes gastrointestinal and hematologic side effects, rather than ototoxicity or nephrotoxicity.

**Option C:** This option is incorrect because cisplatin, a platinum-based chemotherapy agent, does cause ototoxicity, but it is not as commonly associated with nephrotoxicity as aminoglycosides.

**Option D:** This option is incorrect because furosemide, a loop diuretic, can cause nephrotoxicity, but it is not typically associated with ototoxicity.

**Clinical Pearl / High-Yield Fact**
Aminoglycosides should be used with caution in patients with pre-existing renal impairment or hearing loss, and their use should be monitored closely with regular audiograms and serum creatinine levels.

**Correct Answer: C. Cisplatin.**