Forests are "temperature regulators", which are mainly related to their physiological functions () A. Absorption B. Breathing C. Photosynthesis.

Plant transpiration refers to the process that water in plants is emitted into the atmosphere in the form of water vapor. Water absorbs heat from liquid to gas, so it can take away the heat in plants and reduce the temperature of plants, thus reducing the temperature of the environment. Therefore, the forest is a "temperature regulator"; In addition, transpiration provides upward power for plant roots to absorb water and inorganic salts; Transpiration will also increase atmospheric humidity, precipitation and water circulation in the biosphere.

So choose: D.