**Core Concept**
Bacitracin is an antibiotic that inhibits bacterial cell wall synthesis, specifically targeting the dephosphorylation step of the cell wall peptidoglycan layer. This mechanism involves the binding of bacitracin to the enzyme bactoprenol, which is a carrier molecule responsible for transferring peptidoglycan precursors across the bacterial cell membrane.

**Why the Correct Answer is Right**
Bacitracin exerts its antibacterial effect by inhibiting the dephosphorylation of bactoprenol, thereby preventing the incorporation of peptidoglycan precursors into the bacterial cell wall. This results in weakened cell walls and ultimately leads to cell lysis and death. Bacitracin's mechanism of action is particularly effective against gram-positive bacteria, which have a thicker peptidoglycan layer compared to gram-negative bacteria.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect, as bacitracin does not act on protein synthesis. Protein synthesis inhibitors, such as aminoglycosides, target the bacterial ribosome.
**Option B:** Incorrect, as bacitracin does not act on the bacterial cell membrane. Cell membrane-targeting antibiotics, such as polymyxins, interact with the lipid bilayer of the cell membrane.

**Clinical Pearl / High-Yield Fact**
Bacitracin is commonly used in combination with other antibiotics, such as polymyxin B and neomycin, to treat infections caused by gram-positive bacteria. It is also used as a topical antibiotic to prevent wound infections and promote wound healing.

**Correct Answer:** B. Cell wall synthesis