<prompt> The toxigenicity of C.diphtheriae is due to:Beta phageLambda pageGamma phageDelta phage  <response>: The toxigenicity of C.diphtheriae is due to beta phage. Diphtheria Toxin production depends on : Phage coded: Diphtheria Toxin is coded by b corynephage carrying tox gene-toxigenic. Iron concentration: toxin production depends on optimum iron concentration 0.1 mg per liter. DT repressor gene DtxR- iron dependent negative regulator of Diphtheria Toxin production and iron uptake in C.diphtheriae. Biotypes: 3 biotypes with their toxigenicity is as follows : All strains of gravis, 95-99 strains of intermedius, 80-85 of mitis strains are toxigenic. However, toxins produced by different biotypes are antigenically similar. 