Correct Answer - A
The resistance of inductor(coil), `R=12/24 = 0.5Omega`
If phase difference between current and emf is zero, then reactance of circuit will must be zero.
The impedance of the circuit equals to resistance i.e, `Z=0.5Omega`
Now, rms current, `I_(rms) =V_(rms)/Z = 24/0.5 =48 A`