In a circuit where the components are tuned to resonate at a higher frequency than applied, the circuit is most likely a:

A frequency multiplier intentionally uses a non-linear active device to generate harmonics, which are integer multiples of the fundamental input frequency. The output tank circuit is then specifically tuned to resonate at one of these higher frequencies, filtering out the fundamental signal and other unwanted harmonics. In contrast, a linear amplifier is designed to reproduce the input signal with minimal distortion, meaning its output is tuned to the exact same frequency as its input. A frequency divider would be tuned to resonate at a lower frequency rather than a higher one.