Explanation: The RF amplifier is typically the first active stage in a receiver. Its primary purpose is to improve the receiver’s overall noise figure. By providing initial amplification of the extremely weak incoming signal *before* it reaches the noisier mixer and IF stages, it ensures that the signal is boosted above the noise floor of subsequent components. This initial, low-noise amplification is critical for a receiver to detect very weak signals effectively, as the noise contributed by this first stage largely determines the system's overall noise performance. A is incorrect because the majority of a superheterodyne receiver's gain typically comes from the Intermediate Frequency (IF) amplifier stages. B is incorrect; image rejection is determined by the selectivity of the RF front-end filtering *before* the mixer, not by the RF amplifier's gain or AGC. D is incorrect as the AGC voltage is generated by a separate detection circuit and *controls* the gain of the RF amplifier, rather than being developed by it.