You are presented with the question "Cocaine causes what to contract?" and the following answer choices: 
- layers of fat
 - a lot of human deaths
 - Walls of blood vessels.
 - harmful substances
 - the rest of the body
 - metabolic reaction
 - direct damage to the lungs
 - decreases its bodily water

Now knowing that constriction occurs when the muscular walls of blood vessels contract and cocaine constricts the blood vessels, choose the best answer.


 

   Walls of blood vessels.      