Fact 1: Freezing causes a solid to form.

Fact 2: Lower temperature thresholds are at freezing.

Given the two facts above, answer the question "what causes a solid to form?" with the following options: 
- sunlight
 - evaporative cooling
 - gases
 - Physical weathering
 - water evaporation
 - lower temperature thresholds
 - exposure to cold
 - fissures of hot, acidic water


 

      lower temperature thresholds   