Which of the following is a characteristic of the prime meridian?

The prime meridian is a significant geographical reference point that marks the division between the Eastern and Western hemispheres of the Earth. It is established at 0° longitude and serves as the starting point for measuring longitude. By defining this division, it plays a crucial role in navigation, mapping, and geographical information systems. This characteristic helps in understanding the geographical layout of the world, where locations east of the prime meridian are measured in degrees east, and locations west are measured in degrees west.

The other choices do not accurately describe the prime meridian. The prime meridian is not at 45° longitude; rather, it is the zero-degree line of longitude. It does not run horizontally; instead, it runs vertically from the North Pole to the South Pole. Lastly, latitude is measured in degrees north or south of the Equator, with the prime meridian being related to longitude, not latitude, hence it is not located at 90° latitude.