Principle of health education includes: (A) Interest, (B) Know to unknown, (C) Good human relations, (D) All of the above
Answer is D. Principle of health education :

Interst.
Credibility.
Participation.
Motivation.
Reinforcement.
Learning by doing.
Comprehension.
Known to unknown.
Setting an example.
Good human relations.
Feedback.
Leaders.