Explanation: Dual memory systems in radar employ temporal filtering to effectively reduce sea clutter. Sea clutter, caused by radar energy reflecting off ocean waves, is highly variable and appears randomly from one radar sweep to the next. Real targets, such as ships or buoys, are persistent and appear consistently across successive sweeps. The dual memory function digitizes and stores the radar returns from at least two consecutive sweeps. By comparing these stored sweeps, the system can identify and display only those signals that remain constant or appear consistently in both. This process effectively filters out the transient, random echoes of sea clutter, while retaining and highlighting the more stable, desired target signals. Option B is incorrect; dual memory helps detect targets amidst clutter, not make them appear larger. Option C describes Swept Gain or Sensitivity Time Control (STC), which is a different method for reducing close-in clutter by adjusting receiver gain with range. Option D is incorrect, as indiscriminately increasing receiver gain would also amplify clutter.