The correct answer to the question is option-2: Resistance. DC current can be controlled by using resistance in a circuit.

To understand this, let`s look at the other options as well.

Option-1: Impedance refers to the overall opposition to the flow of current in an AC circuit. It consists of both resistance and reactance (a combination of capacitance and inductance). Since the question specifically asks about DC current control, impedance may not be relevant in this context.

Option-3: Capacitance is the ability of a component to store an electrical charge. While it can play a role in controlling AC current, it does not directly control DC current.

Option-4: Inductance is the ability of a component to store energy in a magnetic field. Similar to capacitance, it is more relevant in AC circuits and does not directly control DC current.

Therefore, out of the given options, resistance is the most appropriate choice for controlling DC current. By altering the resistance in a circuit, we can adjust the flow of DC current.