Which term describes a line of reference chosen without geographic necessity?

• A. Arbitrary meridian
• B. Prime meridian
• C. Central meridian
• D. Standard parallel

Answer: (A)

A line of reference chosen without geographic necessity is an arbitrary meridian. This term describes a longitude line set purely for convenience, to orient a map or projection when there’s no natural geographic line that should be used. It’s not tied to any real feature on Earth, so you can pick any longitude that makes the grid easiest to work with or best fits the area being represented.

Other lines are defined by geography or projection design. The prime meridian is fixed by a real Earth reference (Greenwich) and thus geographic. The central meridian is chosen for a specific map projection to minimize distortion across a zone. A standard parallel is a latitude line used in certain projections to control scale behavior, not a meridian. So the only term that fits “chosen without geographic necessity” is the arbitrary meridian.