Which is true about BCG?

d. WHO recommends Danish 1331 for vaccine production(Ref: IAP Guidebook on Immunization 2013-14; pg 113-117, Nelson's 20/e p 3212, Ghai, 8/e p 190-191)Discussing 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 phenomenon"Option dTrue; The two common strains of for use in BCG vaccine are Copenhagen (Danish 1331) and Pasteur