Fact 1: When light enters the eye through the pupil , that light falls on the retina.

Fact 2: Receptors are cells in the retina that perceive light.

Given the two facts above, answer the question "What is used to perceieve light inside the pupil" with the following options: 
- an electron lens
 - It expands
 - Receptor Cells
 - heat energy
 - Energy.
 - focusing a lens
 - sensory neurons
 - observe it


 

   Receptor Cells      