The correct answer is A) relative bearings. Relative bearings refer to the direction of an object in relation to the heading of the observer's vessel. This is the standard way for a look-out to report objects sighted, as it provides the most immediately useful information to the officer in charge for maneuvering the vessel. The other options, true bearings, magnetic bearings, and gyro bearings, are less relevant for a look-out's report as they require additional calculations or equipment to determine. The key purpose of a look-out is to quickly identify and communicate the direction of any observed objects, which is best accomplished using relative bearings.