A junior Thomas Edison wants to make a brighter light bulb. He decides to modify the filament. How should the filament of a light bulb be modified in order to make the light bulb produce more light at a given voltage?
(a) Increase the resistivity only.
(b) Increase the diameter only.
(c) Decrease the diameter only.
(d) Decrease the diameter and increase the resistivity.
(e) Increase the length only.