Which explains what happens to a warm air mass at a cold front? a. a warm air mass overtakes a cold one, and the warm air rapidly rises and cools. the water in the air condenses to form clouds, heavy rain, and thunderstorms. b. a warm air mass overtakes a cold one, and the warm air gradually rises and cools. the water in the air condenses to form clouds and gentle rain. c. a cold air mass overtakes a warm one, and the cold air rapidly pushes the warm air up. the rapidly rising warm air cools, and the water in the air condenses to form clouds, heavy rain, and thunderstorms. d. a cold air mass overtakes a warm one, and the cold air gradually pushes the warm air up. the gradually rising warm air cools, and the water in the air condenses to form clouds and gentle rain.