Which of the following quantities is most directly proportional to the instantaneous brightness of an ideal incandescent lightbulb?
(a) The average electrical power dissipated in the filament since the bulb was switched on
(b) The instantaneous electric power dissipated in the connecting wires leading to the bulb
(c) The instantaneous electric power dissipated in the bulb’s filament
(d) The rate at which the battery supplies electrical energy to the entire circuit