The answer is letter A. Transpiration.
Transpiration is the process of transfer of water or evaporation of water into the atmosphere that chiefly occurs at the leaves of plants during their food process while their stomata are open for carbon dioxide and oxygen to pass. In other words, it is the movement of water and evaporation from a plant's aerial parts like flowers, stems and leaves.
The rate of transpiration depends on environmental factors like light, temperature, humidity, soil water, and wind.
