The correct option is D Evaporation
Clouds form when the invisible water vapor in the air condenses into visible water droplets or ice crystals.
Heated by sunshine, the ground heats the air just above it. That warmed air starts to rise because, when warm, it is lighter and less dense than the air around it. As it rises, its pressure and temperature drop causing water vapor to condense. Eventually, enough moisture will condense out of the air to form a cloud.