Fact 1: Increasing heat causes thermal expansion.

Fact 2: Thermal expansion can cause serious problems.

Given the two facts above, answer the question "Increasing heat causes what?" with the following options: 
- lower temperatures
 - chemical reaction
 - cooler weather
 - serious problems
 - Evaporation
 - global warming
 - kinetic energy
 - refrigeration


 

    serious problems     