Which statement best describes the function of a magnetic compass?

The function of a magnetic compass primarily revolves around its ability to provide a reading based on the Earth's magnetic field. A magnetic compass contains a magnetized needle that aligns itself with the Earth's magnetic field, allowing it to indicate the direction of magnetic north. This fundamental principle is what enables navigators to determine their heading relative to magnetic north, which is essential for navigation.

While it's true that the compass can indirectly indicate the ship's heading and that it differs from true north depending on the geographic location (magnetic declination), the core functionality lies in its interaction with the Earth's magnetic field. Understanding this is crucial for anyone utilizing the compass for navigation, ensuring they use the right adjustments when translating magnetic readings to true bearings.

Other choices may touch on aspects of navigation or ship functions, but they do not accurately encapsulate the primary role of the compass in relation to the magnetic field.