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
Which anti TB drug cause resistance fastest? 
Select and explain. 
A. INH, B. Streptomycin, C. Rifampicin, D. Ethambutol
A: INH
Answer: A: INH 
Explanation: Ans. is 'a' i.e., INH "In patient on antitubercular drugs initial resistance occurs in about 4% of isolates, usually to isoniazid".