This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Health education & planning, Subject name: Social & Preventive Medicine
[{'content': 'Principles of Health education include all Except \nSelect and explain. \nA. Credibility, B. Interest, C. Motivation, D. Unknown to known', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Principles of Health education include: Credibility, Interest, Paicipation, Motivation, Comprehension, Reinforcement, Learning by doing, Known to unknown, Setting an example, Good human relations, Feedback, leadersPark 23e Pg: 862', 'role': 'assistant'}]