Which of the following can be used to determine the Q of a series-tuned circuit?

The quality factor (Q) of a tuned circuit is a measure of its sharpness or selectivity. Mathematically, Q is defined as the ratio of the resonant frequency to the bandwidth (Q = f / BW). Because of this relationship, if you know the resonant frequency and measure the bandwidth of the circuit's frequency response (the 3 dB or half-power points), you can easily calculate the circuit's Q. Distractors like frequency shift or the ratio of inductive to capacitive reactance do not directly yield Q. At resonance, inductive and capacitive reactances are equal, making their ratio exactly 1, which provides no information about the circuit's bandwidth or selectivity.