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
Characters of exotoxin include all, except 
Select and explain. 
A. Protein polysaccharide complex, B. Heat labile, C. Highly potent, D. Has specific tissue affinity
A: Protein polysaccharide complex
Answer: A: Protein polysaccharide complex 
Explanation: None