You are presented with the question "What causes tornadoes? " and the following answer choices: 
- Electrical energy
 - scattered light
 - hypothyroidism
 - Time and energy
 - harmful substances
 - Cold fronts.
 - Tropical
 - heat energy

Now knowing that cold fronts cause thunderstorms as they pass by and thunderstorms Thunderstorms give birth to tornadoes, choose the best answer.


 

      Cold fronts.   