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: Medicine
MDR TB must be treated for at least ? 
Select and explain. 
A. 12 months, B. 18 months, C. 20 months, D. 36 months
C: 20 months
Answer: C: 20 months 
Explanation: Ans. is 'c' i.e., 20 months Resistance (or intolerance) to H Throughout (6) RZE Resistance (or intolerance) to R Throughout (12-18) HZEQ Resistance to H + R Throughout (at least 20 months) ZEQ + S (for another injectable agents) Resistance to all first-line drugs Throughout (at least 20 months 1 injectable agent + 3 of of these 4 ethionamide cycloserine, Q, PAS Intolerance to Z HRE