Explanation
$$\textbf{Concept to be used:}$$
$$\bullet$$ Heating effect of current
$$\textbf{Correct Option: A}$$
$$\textbf{Explanation for Correct option:}$$
$$\bullet$$ The heating effect of electric current is utilised in devices such as electric heater, electric iron etc.
$$\bullet$$ When the electric circuit is purely resistive, that is, a configuration of resistors only connected to a battery; the source energy continually gets dissipated entirely in the form of heat.
$$\bullet$$ The heat is produced in the heating coil of the electric iron given by Joule's law of heating, $$H=I^2Rt.$$
$$\textbf{Explanation for Incorrect option:}$$
Any option containing the case $$B$$ will be incorrect because it demonstrates the magnetic effects of current. So option $$B$$ and $$C$$ are incorrect.
Option $$D$$ is also becomes incorrect because option $$A$$ is correct.
$$\bullet$$ Appliances in an electric circuit work only when the circuit is closed.
$$\textbf{Correct Option: B}$$
$$\bullet$$ The switch is closed in the electric circuit given in option $$B$$. This gives a closed path for the current to flow through the filament of the bulb.
$$\bullet$$ The current is able to flow through the filament and hence the filament will get hot in this case due to the heating effect of current.
$$\bullet \ Option \ A:$$ We don't have to get confused with the wire wound around the box. The switch is open so the electric bulb won't glow and its filament won't get hot.
$$\bullet \ Option \ C:$$ Here also, the switch is open. So the current won't flow through the electric bulb's filament and it won't get hot.
$$\bullet \ Option \ D:$$ Here, though the switch is closed, still the bulb won't glow. It is due to the wrong connection of the cells. The net voltage of these two cells will be zero. The voltage of both cells subtracts each other due to reverse polarity. $$V_{net}=V_o+(-V_o)=0$$
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