What is the equator?

• A. The zero degree line of longitude.
• B. The zero degree line of latitude.
• C. The Prime Meridian.
• D. The Tropic of Cancer.

Answer: (B)

The main idea here is that latitude tells you how far north or south you are from the equator, which is the zero-degree circle around the middle of the Earth. The equator is an imaginary line encircling the globe and marks 0° latitude, meaning locations measured north or south of it have positive or negative latitude values. It also divides the planet into Northern and Southern Hemispheres and is the reference for climate and navigation tied to angular distance along the Earth's surface.

This line is not a line of longitude (which runs from pole to pole and includes the Prime Meridian at 0° longitude). It’s also not a specific latitude like the Tropic of Cancer, which sits at about 23.5° north.