Which component of the VOR instrument is also known as a course selector?

The omnibearing selector (OBS) is the correct answer because it is specifically designed to allow pilots to select their desired course or radial when navigating using a VOR (VHF Omnidirectional Range) navigation aid. The OBS allows the pilot to set the specific bearing they want to follow, relative to the VOR station, thus directing them along a designated flight path.

In practical terms, when a pilot tunes a VOR frequency and uses the OBS, they can adjust the dial to indicate the desired heading to or from the VOR station. This function is critical as it helps pilots maintain their intended course, especially in navigating through complex airspaces or during instrument flight.

In contrast, the heading indicator displays the aircraft's current heading but does not have the capability to select a course; it simply reflects where the aircraft is pointed. The magnetic compass indicates the aircraft's heading as well but relies on magnetic North and is subject to errors due to various factors. Meanwhile, the course deviation indicator works in conjunction with the VOR to display how far left or right the aircraft is from the selected course, but it does not allow for the selection of a course itself.