Here's a problem to solve: Thunderstorms and hurricanes are examples of severe weather. Which of these weather conditions is necessary for the formation of thunderstorms and hurricanes?

Among the 4 following options, which is the correct answer?

- A: a cold rain falling to the ground
 
- B: air masses combining to create a high-pressure area
 
- C: winds spiraling downward and away from the center of a storm
 
- D: air moving toward the center of a storm and rising into the atmosphere
 