The prime meridian is located at A. \( 0^{\circ} \) longitude. B. \( 0^{\circ} \) latitude. \( 180^{\circ} \) longitude. D. \( 180^{\circ} \) latitude.

The prime meridian is a key reference point in geography, establishing a longitudinal baseline at \( 0^{\circ} \) longitude. It runs through Greenwich, London, and serves as the starting point for measuring longitude east and west around the globe, making it crucial for navigation and timekeeping. Besides pinpointing the prime meridian, the concept of latitude comes into play, where \( 0^{\circ} \) latitude is known as the equator. This line divides the Earth into the Northern and Southern Hemispheres, and works in tandem with the prime meridian for a complete geographical grid.