Explanation: To determine a VHF receiver's minimum discernible signal (MDS), you need to find the weakest input signal it can successfully detect above its internal noise. This is achieved by: * **Using a signal generator:** This device produces a controlled, variable-strength radio frequency (RF) signal at a specific frequency. * **Matching frequency:** The signal generator is set to the frequency the receiver is tuned to. * **Adjusting output:** The signal generator's output power is initially set very low (near zero) and then gradually increased. The point at which the signal just becomes audible or discernible above the receiver's background noise (typically heard through the speaker) indicates the MDS. Option B accurately describes this process. Options A and C use test equipment (oscilloscope, spectrum analyzer) that are not directly used at the antenna input to *determine* MDS in this manner. Option D specifies a frequency but lacks the crucial procedural detail of adjusting the signal level to find the minimum discernible point, making it incomplete.