What direction does the meridian of longitude run?

The correct answer is that the meridian of longitude runs north to south. Meridians are the lines on a map that connect the North Pole and South Pole. Longitude measures the angular distance of a point east or west of the Prime Meridian, which is set at 0 degrees. Each meridian is an arc that spans from pole to pole, indicating a specific location in the longitudinal system of geographic coordinates.

In contrast, the other options describe orientations that do not pertain to the nature of longitude. East to west refers to lines of latitude, which run parallel to the equator and measure the distance north or south of it. Diagonal and circular would not accurately characterize the straight, vertical alignment of the lines of longitude. Understanding the orientation of meridians is crucial for navigation and for grasping how we define locations on the Earth's surface.