Option A: The glass case of the bulb does not glow at all. The glass case is to keep all the gases inside and to protect the filament and inner wires of the bulb. So, option (a) is not the correct option.

Option B: The thin filament actually glows up when we switch on the electric circuit. This happens as when we "ON" the switch the electric current flows through the circuit and the flow of current increase the temperature of the filament resulting in the glowing of the filament. It is like when you heat an iron bar too much it turns into a red glowing iron bar.

Option C: The thick wires do not glow in the bulb, they are just for supporting filament and passing the current to it.

Option D: Gases do not glow