Fact 1: Eyes are used for seeing by animals by sensing light.

Fact 2: Light enters the eye through the pupil.

Given the two facts above, answer the question "What are used for seeing by animals by sensing light?" with the following options: 
- photons
 - fingers
 - cactuses
 - ears
 - pupils
 - Decibels
 - noses
 - bullfrogs


 

     pupils    