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: Dental
Which of the following methods of water fluoridation not depend on electric assistance for water flow 
Select and explain. 
A. Venturi fluoridator system, B. Solution feeder, C. Dry feeder, D. Saturator
A: Venturi fluoridator system
Answer: A: Venturi fluoridator system 
Explanation: None