When electricity flows to a light bulb , the light bulb will turn on, and materials that control the flow of electricity are called resistors. Given these facts, what could prevent a light bult from turning on among the following options:
- sensory neurons
 - herbicide
 - A resistor
 - focusing a lens
 - evaporation
 - heat energy
 - heating liquids
 - energy barrier


 

   A resistor      