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
[{'content': 'Incubation period of diphtheria: \nSelect and explain. \nA. 2-3 days, B. 5-7 days, C. 14-15 days, D. 21 days', 'role': 'user'}, {'content': 'Answer: A \nExplanation: 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', 'role': 'assistant'}]