If an object is exposed to direct sunlight. the light-receiving<br/>surface is of the warm color, and the back-light surface is of the<br/>cool color, and the strong light part of the light-receiving side is<br/>relatively in cool color. Part of the back-light side reflected by<br/>the blue sky-light appears cooler, while the other part of the<br/>back-light reflected by the sunlight from the ground is covered with<br/>a layer of( ). A: bright color B: cool gray C: intermediate color D: warm color