You are presented with the question "What can cause cell walls to relax?" and the following answer choices: 
- Decreased light intensity
 - Something coming from a gland
 - matter vibrating
 - Temperature changing
 - Water vapor cooling
 - the Earth being tilted
 - raising their temperature
 - heat produced

Now knowing that dilation occurs when cell walls relax and conversely, a decrease in light intensity causes dilation of the pupils, choose the best answer.


 

 Decreased light intensity        