<prompt> Which one of the following statements about leprosy is true?Group surves for case detection are carried out when prevalence of leprosy is less than 1 per 1000For determining the bacteriological index, in a smear indicates 2 bacilli in every fieldMinimum duration of treatment for paucibacillary cases is for 9 monthsMinimum duration of treatment for multibacillary case is for 12 months  <response>: Duration of Treatment for Multibacillary leprosy-MB blister packs for 12 months,within 18 months. Reference:Park;s textbook of preventive and social medicine,K.Park,23rd edition,page no:324. p 