What genetic pecularity is there in pathogenic/ toxigenic strain of corynebacterium diphtheriae but not in nonpathogenic strain -

Ans. is 'c' i.e., Integrated temperate phage The toxigenicity of the diphtheria bacilli depends on the presence in it of corynephages (tox +). Nontoxigenic strains may be rendered toxigenic by infecting them with beta phage or some other larger phage.This is known as lysogenic conversion or phage conversion.