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
[{'content': 'True about corynebacterium diptheriae is \nSelect and explain. \nA. All types produce toxin, B. Toxin production is dependent upon critical concentration of iron, C. Heat stable toxin, D. Inhibit cAMP', 'role': 'user'}, {'content': "Answer: B \nExplanation: Toxin production is also influenced by the concentration of iron in the medium. The optimum level of iron for toxin production is 0.1mg/ l. The concentration of 0.5 mg / l inhibits the formation of the toxin. Only virulent strain produce powerful exotoxin. It inhibits protein synthesis. It is heat liable. Incubation at 37deg C for 4-6 weeks conve toxin to toxoid. Reference: Textbook of Microbiology; Anathanarayan and panicker's; 10th edition; Page no: 240", 'role': 'assistant'}]