Explanation: Trial Mode in ARPA (Automatic Radar Plotting Aid) equipment serves a critical safety function in navigation. It allows the operator to input a proposed maneuver for their own vessel, such as a change in course or speed. The ARPA then simulates the effect of this hypothetical maneuver on all tracked targets, predicting new Closest Point of Approach (CPA) and Time to Closest Point of Approach (TCPA) values. This enables the navigator to assess the potential outcome of a proposed action, ensuring it safely avoids collisions with other vessels *before* physically altering the ship's actual course or speed. * **Option A** is incorrect because Trial Mode is about future hypothetical maneuvers, not selecting or displaying past target positions. Past positions are part of normal tracking. * **Option B** describes the fundamental role of ARPA in its normal operating mode – tracking targets and displaying collision assessment data. While Trial Mode uses this data, its specific purpose is to simulate *changes* to that data based on a proposed maneuver.