Use reasoning to lead to the answer of the following question:
Billy turned off the water by using the diaphragm. A diaphragm is a type is what?\nOptions:\n- drugstore\n- human\n- bivalve\n- valve\n- gas pump
 Reasoning process:
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Valve is a device for controlling the passage of fluid or air through a pipe, duct, etc., especially an automatic device allowing movement in one direction only. Billy turned off the water by using the diaphragm. A diaphragm is a type of Valve. Therefore, the final answer is valve.
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