This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteria, Subject name: Microbiology
[{'content': 'Corynebacterium diphtheria is \nSelect and explain. \nA. Gram-positive cocci, B. Gram-positive bacilli, C. Gram-negative cocci, D. Gram-negative bacilli', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ref: Harrisons 19th ed. pg. 978* C. diphtheriae is a Gram-positive bacillus that is unencapsulated, nonmotile, and nonsporulating.* The bacteria have a characteristic club-shaped bacillary appearance and typically form clusters of parallel rays, or palisades, that are referred to as "Chinese characters"', 'role': 'assistant'}]