The process or arrangement, which keeps the engine speed constant (according to the changing load conditions) is known as governing of IC engines. In Diesel engine, the method of governing employed is quality governingwhich monitors the speed andload on the unit and regulates the fuel injection system to attempt to hold the constant speed or load.

Some IC engines governing methods :

1. Hit and miss governing: In this system of governing, whenever the engine starts running at higher speed (due to decreased load), some explosions are omitted or missed. This is done with the help of a centrifugal governor. This method of governing is widely used for IC engines of smaller capacity or gas engines.

2. Qualitative governing: In this system of governing, a control valve is fitted in the fuel delivery pipe, which controls the quantity of fuel to be mixed in the charge. The movement of control valve is regulated by the centrifugal governor through rack and pinion arrangement.

3. Quantitative governing: In this system of governing, the quality of charge (i.e. air-fuel ratio of the mixture) is kept constant. But the quantity of mixture supplied to the engine cylinder is varied by means of a throttle valve which is regulated by the centrifugal governor through rack and pinion arrangement.

4. Combination system of governing: In this system of governing, the qualitative and quantitative methods of governing are combined together.

Hence, the correct option is (A).