The correct answer is: A. Applied voltage decreases but current increases.
In a pure inductive circuit, the current lags the voltage by 90 degrees. This means that the current is at its maximum when the voltage is zero, and the current is zero when the voltage is at its maximum.
When the applied voltage decreases, the current will increase. This is because the inductor will store energy in the magnetic field when the voltage is applied. When the voltage is decreased, the inductor will release this energy, causing the current to increase.
The other options are incorrect because they do not take into account the phase relationship between the voltage and current in a pure inductive circuit.
Option B: Applied voltage increases but current decreases. This is not possible in a pure inductive circuit, because the current always lags the voltage by 90 degrees.
Option C: Both applied voltage and current increase. This is possible, but it does not mean that the circuit is taking power from the A.C. line. In fact, the circuit is actually storing energy in the inductor when the voltage and current are both increasing.
Option D: Both applied voltage and current decrease. This is not possible in a pure inductive circuit, because the current always lags the voltage by 90 degrees.