Explanation: A RADAR unit's magnetron generates very high-power RF pulses for transmission. The Automatic Frequency Control (AFC) section of the receiver continuously monitors the magnetron's output frequency to maintain stability and accuracy. Because the magnetron's output power is extremely high and the AFC circuitry is sensitive and designed for much lower signal levels, an RF attenuator is placed between them. This attenuator safely reduces a small sample of the magnetron's output power to a level suitable for the AFC circuit. This allows precise frequency measurement and feedback control without damaging the delicate receiver components. Placing an attenuator between the antenna and receiver (A) would weaken crucial echo signals. Between the magnetron and antenna (B) would severely reduce transmitted power and the radar's range. The AFC section provides control signals, not RF power, so an attenuator between it and a klystron (D) does not fit the typical signal path.