Fact 1: Ultraviolet light causes sunburn.

Fact 2: Sunburns cause the skin to become red and painful to the touch.

Given the two facts above, answer the question "What causes skin to become red and painful to the touch?" with the following options: 
- skin lotion
 - chemical messengers
 - lightening creams
 - chemical reaction
 - ultraviolet light
 - lightening skin
 - sensory neurons
 - deoxyribonucleic acid


 

     ultraviolet light    