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': 'Corynebacterium diphtheria produce black or grey colonies on the following agar \nSelect and explain. \nA. Mac-conkey agar, B. Potassium tellurite agar, C. Thayer main medium, D. Tinsdale agar', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Corynebacterium produce black or grey colonies on potassium tellurite blood agar It acts as a selective medium for its growth Ref: Textbook of Microbiology Baveja 5th ed Pg 211', 'role': 'assistant'}]