You are presented with the question "What causes a refraction of light?" and the following answer choices: 
- 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

Now knowing that water causes refraction of light and water is a compound of hydrogen and oxygen, choose the best answer.


 

 compound of hydrogen oxygen        