The great circle concept is most closely tied to:

• A. The intersection of a plane that passes through Earth's center with the Earth's surface.
• B. A circle of latitude at any fixed distance from the equator.
• C. A circle formed by intersecting a plane tangent to the Earth's surface.
• D. The equator only.

Answer: (A)

A great circle is formed by the intersection of a plane that passes through Earth's center with the surface, producing the largest possible circle on the globe. This is why it represents the shortest path between two points on a sphere, a key idea in navigation for plotting efficient routes. A circle of latitude is not a great circle because most latitudes lie on planes that do not go through the center, so they are smaller circles except for the equator. A plane tangent to the surface would touch at a single point, not create a circle on the sphere. The equator is a great circle, but the concept applies to any plane through the center, not just the equator.