Power factor is one for
A. pure resistor
B. pure inductor
C. pure capacitor
D. either inductor or capacitor

Hint: Power is used to measure work in two different contexts, one in the terms of mechanical work and the other in terms of electrical work. In mechanics, power is the energy consumed by doing one joule of work for one second. i.e. $1W=\dfrac{1J}{1s}$. And in electrical terms, it is given as the current flow of $1\;A$ of $1\;V$. i.e. $1W=1A\times 1V$.
Formula: $P.F=\dfrac{R.P}{A.P}$

Complete answer:
In an AC circuit, if $R$ is the resistance when connected to say $V$ source gives $I$ current, then the $P$ power is given as $P=I^{2}_{rms}R=\dfrac{{(V_{rms})}^{2}}{R}$, which is the real power.
Also, in an LCR combination circuit, $Z$ is the impedance of the circuit or the total resistance offered by the circuit, it is given as $Z=\sqrt{R^{2}+(X_{L}-X_{C})^{2}}$. Where, $X_{L},X_{C}$ are the inductive reactance and the capacitive reactance. Then the power due to the circuit is given as $P=I^{2}_{rms}Z=\dfrac({V_{rms}}{Z})^{2}Z$ which is called the apparent power.
Then the power factor is defined as the ratio of real power to the apparent power in the circuit. This value varies from $0-1$.
$P.F=\dfrac{R.P}{A.P}$
If the power factor is $0$, then there is some impedance in the circuit.
If the power factor is $1$, then the circuit is said to be resistive in nature $Z=R$, and here maximum power is used to do work.

Thus the answer is option A. pure resistor

Note:
The unit of power is watt, and it is named after the scientist Watt, who discovered the steam engine. Power factor is only taken into account when an AC is passed through an LCR combination, like LC, LR, RC or LCR in series or parallel connection.