You are presented with the question "What could prevent a light bult from turning on?" and the following answer choices: 
- sensory neurons
 - herbicide
 - A resistor
 - focusing a lens
 - evaporation
 - heat energy
 - heating liquids
 - energy barrier

Now knowing that when electricity flows to a light bulb , the light bulb will turn on and materials that control the flow of electricity are called resistors, choose the best answer.


 

   A resistor      