The correct answer is D) running fix. The position labeled "C" on the illustration D051NG represents a running fix, which is a position determined by taking two or more direction lines or bearings at different times and advancing the earlier line(s) to the time of the later bearing. This allows the navigator to plot the vessel's position between fixes, improving the accuracy of the vessel's track. The other answer choices are incorrect because: A) An estimated position is a position determined by dead reckoning, not by taking multiple bearings. B) A fix is a single position determined by taking a bearing or other means at a specific time. C) A dead reckoning position is a position determined solely by course and speed, without the use of navigational aids.