This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Microbiology
Clinical diphtheria is caused by 
Select and explain. 
A. Corynebacterium diphtheriae, B. Corynebacterium parvum, C. Corynebacterium Ulcerans, D. Streptococcus pyogenes
A: Corynebacterium diphtheriae
Answer: A: Corynebacterium diphtheriae 
Explanation: 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 panicker's; 10th edition; Page no: 240