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
Resistance to zidovudine develops due to : 
Select and explain. 
A. Mutation at reverse transcriptase, B. Increased efflux of the drug from inside the cell, C. Increased metabolism of the drug, D. Decreased zidovudine 5 triphosphate formation
A: Mutation at reverse transcriptase
Answer: A: Mutation at reverse transcriptase 
Explanation: None