<prompt> Clinical diphtheria is caused byCorynebacterium diphtheriaeCorynebacterium parvumCorynebacterium UlceransStreptococcus pyogenes  <response>: Corynebacterium diphtheriae is the causative agent for diphtheria. The incubation period is 3-4 days. The site of infections is faucial, nasal, otitic, laryngeal, cutaneous. According to clinical severity, malignant, septic and hemorrhagic types are there. Reference: Textbook of Microbiology; Anathanarayan and panickers; 10th edition; Page no: 240 