Fact 1: Alight bulb is used for seeing in the dark.

Fact 2: Humans are unable to see clearly in the dark.

Given the two facts above, answer the question "What helps humans see?" with the following options: 
- layers of fat
 - electricity
 - food
 - focusing a lens
 - shadows
 - dolphins
 - Light bulbs
 - pets


 

       Light bulbs  