Explanation: As a DC motor's armature rotates, its windings move through the magnetic field created by the motor's poles. This motion induces a voltage within the armature windings. According to Lenz's Law, this induced voltage opposes the applied line voltage that caused the rotation in the first place. This opposing voltage is specifically called **Counter EMF** (electromotive force). The net voltage across the armature is the difference between the applied line voltage and the Counter EMF. By reducing this net voltage, the Counter EMF effectively limits the armature current, preventing it from becoming excessively high, especially at startup or under varying loads. EMF (A) is a general term for any induced voltage, while Counter EMF (B) specifically describes this opposing voltage in a motor. "Opposition EMF" (C) is not a standard technical term.