Fact 1: Water causes refraction of light.

Fact 2: Water is a compound of hydrogen and oxygen.

Given the two facts above, answer the question "What causes a refraction of light?" with the following options: 
- compound of hydrogen oxygen
 - focusing a lens
 - that material's properties
 - photosynthetic pigments?
 - oxidation reaction
 - a hemisphere is tilted away from the sun
 - sunlight beams
 - solid, liquid, gas


 

 compound of hydrogen oxygen        