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: Social & Preventive Medicine
All of the following can be done with Individual as a unit except 
Select and explain. 
A. Drug administration, B. Health education, C. Vaccination, D. Case report
B: Health education
Answer: B: Health education 
Explanation: Health education can be done individually BUT limitation is that the numbers we reach is really small, and health education is given to only those who come in contact with health system.