Ans. C. 6 drugs for 6 months; 4 drugs for 18 months* Resistance to rifampicin and isoniazid is termed as multiple-drug-resistant TB (MDR-TB). In such a case, 6 drugs are used for 6-9 months in an intensive phase followed by 4 drugs for 18 months in a continuous phase.* The number of drugs used for specific duration in a particular type of TB is given below:Type of TBNumber of Drugs UsedNon-drug resistant - New case4 drugs for 2 months + 3 drugs for 4 monthsNon-drug resistant - Previously treated5 drugs for 2 months + 4 drugs for 1 month + 3 drugs for 5 monthsRifampicin resistance + Isoniazid sensitive7 drugs for 6-9 months + 5 drugs for 18 monthsMDR-TB6 drugs for 6-9 months + 4 drugs for 18 monthsXDR-TB7 drugs for 6-12 months + 6 drugs for 18 months