Answer:
D. Vertical wind shear
Step-by-step explanation:
Wind direction and/or speed must change with height in order for a tornado to form. This is also known as vertical wind shear. Vertical wind shear occurs when the direction and/or speed of the wind changes with height. In the case of a tornado, this can occur when there is a strong updraft, or upward-moving air, near the ground, and a strong downdraft, or downward-moving air, at higher altitudes. This creates a rotating column of air, which can become a tornado if the conditions are right. Vertical wind shear is an important factor in the formation of tornadoes, and is one of the key meteorological conditions that must be present in order for a tornado to develop.