_______ reduces the water loss through the epidermis of aerial parts of the plant.

Concept: The loss of water in the form of water vapor through the aerial parts of a plant is known as transpiration. The loss of water in plants takes place through the stomata. Closing stomata can reduce the water loss through the epidermis of aerial parts of the plant.

Therefore, the correct answer is closing of the stomata.

Hence, the correct answer is option A.