Fact 1: Cold fronts cause thunderstorms as they pass by.

Fact 2: After the cold front passes, be prepared for clear, cold days ahead.

Given the two facts above, answer the question "be prepared for clear, cold days after what" with the following options: 
- global warming
 - spring
 - droughts
 - heat waves
 - thunderstorms
 - Dehydration
 - Greenhouse gases
 - Animal survival


 

     thunderstorms    