Ans. is *a' i.e., To avoid emergence of persistors 6. Two phase chemotheraphyo There are two phase of treatment of tuberculosisIntensive phaseThis is short phase in the early course of treatment and lasts for 1-3 months.Three or more drugs are given to kill as many bacilli as possible, w hich prevents emergence of persisters.The risk of re lapse is also lessened.Continuation phaseIt is aimed at sterilizing the smaller number of dormant or persisting bacilli,o Multidrug treatment in TB is given to -Prevent emergence of persistersPrevent relapsePrevent emergence of resistanceShorten the duration of treatment