A fully charge capacitor C either initial charge q is connected to a coil of self inductance. L at $t=0$ the time at which the energy is stored equally between electric and magnetic field is

Question

$(a)\;\pi \sqrt {LL} \\ (b)\;\frac{\pi}{4} \sqrt {Ll} \\(c)\;2 \pi \sqrt {Ll} \\(d)\;\sqrt {LL} $