In an electrical circuit R, L, C and an a.c. voltage source are all connected in series. When L is removed from the circuit, the phase difference between the voltage and the current in the ciruit is $\frac{\pi}{3}$ . If instead, C is removed from the circuit, the phase difference is again $\frac{\pi}{3}$ . The power factor of the circuit is

Question

( A ) $\frac{\sqrt3}{2}$
( B ) $\frac{1}{\sqrt2}$
( C ) $\frac{1}{2}$
( D ) 1