A LCR series circuit driven with $$E_{rms} = 90$$ V at frequency $$f_d = 30$$ Hz has resistance $$R = 80$$ $$\Omega$$, an inductance with inductive reactance $$X_L = 20.0$$ $$\Omega$$ and capacitance with capacitive reactance $$X_C = 80.0$$ $$\Omega$$. The power factor of the circuit is _______.

A

0.8

B

0.64

C

0.9

D

0.5