Answer:
(c) heat resulting from compressing air that is supplied for combustion
Explanation:
In a diesel engine the combustion of the fuel takes place due to the adiabatic compression which leads to elevated temperatures in the cylinder. First the air is compressed by the piston in the cylinder which raises the temperature, then the atomized fuel is put in the cylinder causing the ignition of fuel. Diesel engines have the highest thermal efficiency.
Spark causes ignition in petroleum engine.
