Which statement correctly describes a meridian?

Which statement correctly describes a meridian?

• A. A Great Circle Formed by a Plane That Contains the Earth's Axis
• B. A Great Circle Formed by a Plane That Contains the Earth's Axis and Passes Through the Poles
• C. A Small Circle Formed by a Plane Not Through the Center
• D. A Line of Longitude

Answer: (B)

A meridian is a line of longitude defined by a great circle that passes through both poles. Geometrically, this means the plane creating that circle must contain the Earth’s axis, and the circle itself intersects the surface at the North and South Poles. So the precise description is: a great circle formed by a plane that contains the Earth’s axis and passes through the poles. This captures both the pole-to-pole path and the axis-based geometry that defines every meridian. Restating it as a line of longitude also helps intuition, but the key point tested here is that a meridian corresponds to a great circle whose plane runs through the axis and that intersects the poles.

A meridian is a line of longitude defined by a great circle that passes through both poles. Geometrically, this means the plane creating that circle must contain the Earth’s axis, and the circle itself intersects the surface at the North and South Poles. So the precise description is: a great circle formed by a plane that contains the Earth’s axis and passes through the poles. This captures both the pole-to-pole path and the axis-based geometry that defines every meridian.

Restating it as a line of longitude also helps intuition, but the key point tested here is that a meridian corresponds to a great circle whose plane runs through the axis and that intersects the poles.