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
Welfare officer is appointed in factories when no of workers are more than 
Select and explain. 
A. 350, B. 500, C. 1000, D. 5000
B: 500
Answer: B: 500 
Explanation: None