Correct option is C
Under-Excitation (Low Excitation): When the motor is under-excited, it draws lagging reactive power from the supply, resulting in a high armature current. This is because the motor is operating at a power factor lower than unity (lagging).
Over-Excitation (High Excitation): When the motor is over-excited, it supplies leading reactive power to the system. In this case, the motor operates at a power factor higher than unity (leading), and the armature current also tends to increase.
