A resistor R, an inductor L and a capacitor C are connected in series to an oscillator of frequency n. If the resonant frequency is ${n}_{r}$,then the current lags behind voltage, when :
• A
$n=0$
• B
$n<{n}_{r}$
• C
$n={n}_{r}$
• D
$n>{n}_{r}$