You are presented with the question "Vapor pressure is caused when" and the following answer choices: 
- liquids expand
 - It gets heated up
 - liquids condense
 - liquids are heated
 - Evaporation
 - Light passing through water
 - Water expanding
 - liquids freeze

Now knowing that boiling is when liquids are heated above their boiling point and vapor pressure is about liquids boiling, choose the best answer.


 

    liquids are heated     