In a series LR circuit with XL=R, power factor is P1. If a capacitor of capacitance C with XC=XL is added to the circuit, the power factor becomes P₂. The ratio of P1 to P₂ will be:

a) P1:P₂ = 1:1
b) P1:P₂ = 2:1
c) P1:P₂ = 1:2
d) P1:P₂ = 1:√2