Answer: b. green year around.
The deciduous forests are found in the North America, northeastern Asia, and western Eurasia. The trees in these forests exhibit thick bark, broad leaves and they shed their leaves in the winter season as these forests remain dry in winter seasons. These trees conserve water by shedding their leaves, as the water may loose by the process of transpiration. They regrow new foliage in the suitable growing season.
Therefore, green year around is the correct option as the decidous forests shed their leaves once in a year.