This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Bacitracin acts on : 
Select and explain. 
A. Cell wall, B. Cell membrane, C. Nucleic acid, D. Ribosome
A: Cell wall
Answer: A: Cell wall 
Explanation: Bacitracin acts by inhibiting the synthesis of the cell wall.
Other polypeptide antibiotics like polymyxin B, colistin and tyrothricin act by an affecting membrane.