This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Health care of community & international health, Subject name: Social & Preventive Medicine
Health care worker is 
Select and explain. 
A. X ray technician, B. Hospital electrical engineer, C. Staff nurse, D. All the above
D: All the above
Answer: D: All the above 
Explanation: Ref:Park's Textbook of Preventive and Social Medicine 25th Ed