This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
[{'content': 'Characters of exotoxin include all, except \nSelect and explain. \nA. Protein polysaccharide complex, B. Heat labile, C. Highly potent, D. Has specific tissue affinity', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]