Examine the map of the United States. Tornadoes are most common in the Midwest and Great Plains states. According to the map, what causes the prevalence of tornadoes in these regions? A) Falling air currents form from the mixing of falling warm, moist air and the rising of cold air. B) Spinning air currents form from the mixing of rising warm, moist air and the falling of cold air. C) Spinning air currents form when cold, dry air becomes saturated with moisture and becomes unstable. Eliminate D) Rising air currents form from the deposition of cold air at the surface and moist air at the top of the troposphere.