Correct option is D
In a four-stroke internal combustion engine, the minimum temperature inside the engine cylinder typically occurs at the beginning of the suction stroke. During this stroke, the intake valve opens, and the piston moves downwards, creating a vacuum that draws in fresh air (in a diesel engine) or an air-fuel mixture (in a petrol engine) from the intake manifold. Since this is the start of the process and no combustion has occurred yet, the temperature inside the cylinder is at its lowest point, closely corresponding to the ambient air temperature or slightly above it.
