What receiver stage combines a 14.25-MHz input signal with a 13.795-MHz oscillator signal to produce a 455-kHz intermediate frequency (IF) signal?

A mixer is a non-linear circuit designed to combine two different frequencies—typically an incoming RF signal and a local oscillator signal—to produce new frequencies. These new frequencies are the sum and the difference of the original two inputs. In this specific scenario, subtracting the 13.795-MHz oscillator frequency from the 14.25-MHz input signal yields exactly 0.455 MHz, or 455 kHz. This 455 kHz difference is the intermediate frequency (IF) used in the superheterodyne receiver. The other options serve different roles. A VFO (Variable Frequency Oscillator) generates the 13.795-MHz signal but doesn't do the combining itself. A BFO (Beat Frequency Oscillator) is used much later in the receiver to demodulate CW or SSB signals, and a multiplier simply increases a single frequency by an integer multiple.