Explanation: The Electronic Bearing Line (EBL) is a crucial tool on radar displays used for navigation and target plotting. It is a user-adjustable line originating from your vessel's position on the radar screen. Mariners rotate the EBL until it bisects a specific target, allowing them to accurately determine and read the target's bearing relative to their own vessel or to true north. Therefore, option D is correct because an EBL specifically serves as a visual and measurable line from your own vessel to a designated target to ascertain its bearing. Options A and B refer to fixed reference lines on a radar display—the ship's heading line indicates its bow direction, and a true north line provides a navigational reference. Option C describes a function often performed in conjunction with a Variable Range Marker (VRM), where the EBL helps pinpoint the target, but the EBL's primary role is measuring bearing, not distance itself.