The correct choice is (c) Float chamber
To explain: Float chamber is a reservoir to maintain a constant level of fuel in the carburettor. Fuel comes from the tank to the float chamber. There is a hollow float provided with a needle. With the level of the fuel going down, the float with the needle also goes down allowing the fuel to come into the float chamber from the fuel tank. As the fuel level goes up, the needle closes the passage and hence a constant level in float chamber is always maintained.