When 100 volt dc is applied across a coil, a current of 1A flows through it. When 100 volt ac at 50 cyle `s^(-1)` is applied to the same coil, only 0.5 A current flows. The impedance of the coil is,
Options:
(a) `100Omega`
(b) `200Omega`
(c) `300Omega`
(d) `400Omega`