Explanation: RADAR systems produce powerful electromagnetic fields that can induce unwanted signals in communications receivers, leading to interference. **Properly grounding, bonding, and shielding all units** (B) are fundamental electromagnetic compatibility (EMC) techniques. * **Shielding** creates an electromagnetic barrier (a Faraday cage) around the receiver's sensitive internal circuits, preventing external RADAR electromagnetic fields from entering and causing interference. * **Grounding** provides a common electrical reference point, diverting stray currents and unwanted noise away from the signal path. * **Bonding** ensures all conductive enclosures and chassis parts are at the same electrical potential, preventing them from acting as antennas or creating ground loops that pick up interference. Together, these measures minimize the pickup of external noise and provide a stable operating environment for the receiver. **Not operating other devices when RADAR is in use** (A) might reduce other sources of interference, but it doesn't address the RADAR interference itself. **Using a high-pass filter on the power line** (C) would block low frequencies and pass high frequencies. Since RADAR operates at high frequencies, this filter would be ineffective or potentially worsen the problem if interference is coupled via the power line. A low-pass or band-stop filter might be considered for conducted power line noise, but it's not the primary solution for radiated RADAR interference into the receiver's RF stages. **Using a link coupling** (D) is a method for transferring RF energy between circuits, offering some isolation, but it's not a general solution for eliminating external RADAR interference to an entire receiver system.