Latitude measures distance in relation to which location?

Latitude measures distance north or south of the Equator, which is defined as 0 degrees latitude. It serves as the baseline for determining how far a location is from this central line, with locations north of the Equator having positive latitude values (up to 90 degrees at the North Pole) and locations south of the Equator having negative latitude values (down to -90 degrees at the South Pole). Therefore, understanding latitude fundamentally links it to the Equator as the reference point for this measurement.

The other choices do not serve as baseline markers for latitude. The Prime Meridian is crucial for measuring longitude, not latitude, while Boston is a specific city and Greenwich is important for longitude as well but not for measuring latitude itself.