This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Corynebacterium, Subject name: Microbiology
Incubation period of diphtheria: 
Select and explain. 
A. 2-3 days, B. 5-7 days, C. 14-15 days, D. 21 days
A: 2-3 days
Answer: A: 2-3 days 
Explanation: Ans. (a) 2-3 daysRef: Harrison's 18th ed. Ch 138Harrisons states: "The incubation period for respiratory diphtheria is 2-5 days; however, disease can develop as long as 10 days after exposure"Types of Diphtheria Infections are1. Faucial (tonsillar pharyngeal)- Commonest type, grey with white pseudomembrane and cervical lymphade- nopathy (bull neck) + toxemia2. Laryngeal - Most severe form3. Nasal - Mildest form4. Cutaneous form - Only non toxigenic strain, punched- out ulcer5. Other form - Conjuctival, otic, genital