Explanation: In an AC circuit, an inductor opposes changes in current flow. When an alternating voltage is applied across a pure inductor, the inductor's magnetic field must build up and collapse. For the current to increase and build this field, the voltage must already be present and changing. This inherent opposition to current change causes the current waveform to reach its peak *after* the voltage waveform reaches its peak. In an ideal, purely inductive circuit, this phase difference is precisely 90 degrees. We say the current *lags* the applied voltage. * **A) Correct:** Current lags voltage by 90 degrees in a purely inductive circuit (remember "ELI the ICE man" – Voltage (E) leads Current (I) in an Inductor (L)). * **B) Incorrect:** Current leading voltage by 90 degrees occurs in a purely capacitive circuit. * **C) & D) Incorrect:** A 45-degree phase shift would occur in an AC circuit containing both resistance and reactance (e.g., an RL or RC circuit), where neither the resistor nor the reactor acts alone or dominates completely.