In a superheterodyne receiver, which stage rejects signals on adjacent channels?

In a superheterodyne receiver, the Intermediate Frequency (IF) filter is primarily responsible for the receiver's selectivity. Once the incoming signal is converted to a fixed IF, it passes through this filter, which is designed with a specific, tight bandwidth. Because the IF filter has steep skirts and a narrow passband, it effectively blocks out nearby frequencies. This is what prevents signals on adjacent channels from interfering with the station you are trying to hear. Other stages serve different purposes: the mixer translates the frequency, the product detector extracts audio from SSB/CW signals, and the limiter removes noise in FM receivers.