Problem: On the Arctic tundra, it is often very windy and extremely cold, but temperatures and wind speed are much more favorable within 30 cm (about 12 inches) off the ground. Included among the plant community in the tundra biome is a species of tree called a willow. Elsewhere, in more southern, warmer parts, willow trees can grow 10 to 12 m (30 to 40 feet ) tall. However, on the Arctic tundra, willows are rarely taller than 30 to 40 cm (12 to 14 inches) with their branches spreading along the ground rather than being upright. This saves the trees from rapid changes in temperature and from extreme cold. This also allows them to become completely covered in snow (an insulating blanket) for further protection during winter. This is an example of ______. Group of answer choices Mutation Genetic drift Gene flow (migration) Natural selection All of the above