Which component prevents fuel from draining from the wing tank?

The float valve is the correct component that prevents fuel from draining from the wing tank in an aircraft. This valve operates based on the level of fuel within the tank. When the fuel level is above a certain threshold, the float rises and closes the valve, effectively sealing the tank and preventing fuel from flowing out. This mechanism is crucial for maintaining fuel levels during various flight phases and ensuring that the aircraft has adequate fuel supply for operation.

The other components listed do not serve this specific function. The check valve typically allows flow in one direction only and would not maintain fuel in a wing tank by preventing drainage. The fuel nozzle is designed for dispensing fuel into the engine rather than preventing drainage. The transfer pump is responsible for moving fuel from one tank to another or to the engine but does not directly prevent fuel from draining from a tank.