You are presented with the question "What powers a light bulb?" and the following answer choices: 
- structure and function
 - The tungsten filament
 - photosynthetic pigments?
 - Unplugging a lamp
 - heat production
 - heat is produced
 - Unscrewing a light bulb
 - The flow of electrical current

Now knowing that aswitch is used to start the flow of current in an electrical circuit and with switch closed, electricity flows through wires, switch and bulb, to light up the bulb, choose the best answer.


 

        The flow of electrical current 