Which stage of a superheterodyne receiver lies between a tuneable stage and a fixed tuned stage?

In a superheterodyne receiver, the fundamental process involves converting a wide range of incoming radio frequencies (RF) into a single, constant intermediate frequency (IF). The stage that receives the incoming RF is the tunable stage, while the IF amplifier is the fixed tuned stage. The mixer is the critical component that sits directly between these two stages in the signal path. It takes the variable RF signal and combines it with a signal from the local oscillator to produce the fixed IF signal through heterodyning. Distractors such as the IF amplifier are incorrect because they represent the fixed stage itself, not the bridge between the tunable and fixed sections. The local oscillator provides a signal to the mixer but does not sit in the main signal path between the RF and IF stages.