**Core Concept**
The question is testing the association between a specific antibiotic and its adverse effect on fetal high-tone hearing loss. This is related to the concept of antibiotic teratogenicity, which refers to the potential of certain antibiotics to cause birth defects or developmental abnormalities in the fetus.

**Why the Correct Answer is Right**
Aminoglycoside antibiotics, such as Gentamicin, are known to be ototoxic, meaning they can cause damage to the inner ear and lead to hearing loss. This ototoxic effect is particularly concerning during pregnancy, as it can cause fetal high-tone hearing loss. Gentamicin works by binding to the 30S subunit of the bacterial ribosome, inhibiting protein synthesis and ultimately leading to bacterial cell death.

**Why Each Wrong Option is Incorrect**
* **Option A:** Cephalosporins are a class of beta-lactam antibiotics that are generally considered safe during pregnancy. While they can cause fetal harm if used excessively, they are not typically associated with ototoxicity or high-tone hearing loss.
* **Option B:** Macrolides, such as Erythromycin, are another class of antibiotics that are often used during pregnancy. However, they are not typically associated with ototoxicity or high-tone hearing loss, making them a less likely choice.
* **Option C:** Tetracyclines are a class of broad-spectrum antibiotics that are contraindicated during pregnancy due to their potential to inhibit bone growth and cause tooth discoloration. However, they are not typically associated with ototoxicity or high-tone hearing loss.

**Clinical Pearl / High-Yield Fact**
When prescribing antibiotics during pregnancy, it is essential to choose agents that are known to be safe for the fetus. Aminoglycoside antibiotics, such as Gentamicin, should be used with caution and only when absolutely necessary, as their ototoxic effects can be devastating.

**Correct Answer: C. Gentamicin**