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: Dental
[{'content': 'Activity of all disinfectants is: \nSelect and explain. \nA. Reduced by organic debris or blood, B. Increased with heat, C. Hastened by adding 5% oxygen, D. Nullified by ethylene dioxide gas', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]