The correct option is B fused bulb
In order to make the bulb glow, the given electric circuit should be closed. The current flows only in closed electric circuit and does not flow in case of an open electric circuit.
1. If the object P is a conducting wire, it will complete the circuit and current will flow which makes the bulb glow. So, it is an incorrect option.
2. Fused bulb has broken filament. If object P is a fused bulb then it will break the circuit and the current does not flow. Thus, the bulb will not glow. So, it is the correct option.
3. If switch connected in a circuit is in ON state then it will conduct electricity. Thus, it will help the bulb to glow. So, it is an incorrect option.
4. If object P is an electric cell whose positive terminal is connected to negative terminal of the given cell then it will form a battery which enhance the brightness of the bulb. So, it also incorrect option.