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: Microbiology
Drug resistance in MTB is due to 
Select and explain. 
A. Conjugation, B. Transformation, C. Transduction, D. Chromosomal mutation
D: Chromosomal mutation
Answer: D: Chromosomal mutation 
Explanation: Mutational drug resistance plays a major role in Mycobacterium tuberculosis.