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
MDR tuberculosis is defined by - 
Select and explain. 
A. Resistance to all first and second line anti-tubercular agents, B. Resistance to any three first line anti-tubercular agents, C. Resistance to all first line and any three classes of second line anti-tubercular agents, D. Resistance to isoniazid and rifampicin
D: Resistance to isoniazid and rifampicin
Answer: D: Resistance to isoniazid and rifampicin 
Explanation: Ans. is 'd' i.e., Resistance to isoniazid and rifampicin o MDR is defined as resistance INH and rifampicin with or without resistence to other drugs. XDR is defined as resistance to INH and rifampicin as well as to all fluoroquinolones and one of injectable drugs (capreomycin, kanamycin, amikacin).