Correct option is (c) RF stage
For explanation I would say: Ability of receiver to selected only wanted signal, and reject other frequencies, out of the various incoming signals, helps the receiver to operate more efficiently. However, at times, the RF amplifier allows a frequency lying close to the desired frequency, to pass to the next stage. This other frequency is undesired and later on is responsible for production of image frequency. Thus, noise is usually developed at RF stage.