<prompt> Which is true about BCG?Distilled water is used as diluentSite for injection is cleaned with spiritMantoux test positive in 6 weeksWHO recommends Danish 1331 for vaccine production  <response>: d. WHO recommends Danish 1331 for vaccine productionRef: IAP Guidebook on Immunization 2013-14; pg 113-117, Nelsons 20e p 3212, Ghai, 8e p 190-191Discussing about the options one by one,Option aFalse; Sterile normal saline may be used as diluent for BCGOption bFalse; For BCG Vaccination, the selected site may be swabbed clean using sterile saline and local antiseptics should be avoidedOption cFalse; Of BCG vaccine recipients whose initial tuberculin skin test is negative, 10-25 will have a positive tuberculin skin test if they are retested within 1-4 weeks--the so-called booster phenomenonOption dTrue; The two common strains of for use in BCG vaccine are Copenhagen Danish 1331 and Pasteur 