Through which city does the Prime Meridian pass, making it commonly called the Greenwich meridian?

• A. Greenwich, England
• B. Paris
• C. Rome
• D. Cairo

Answer: (A)

The main idea is that the Prime Meridian is the line of longitude designated as 0 degrees, serving as the reference point from which east–west measurements are made. This line runs from the North Pole to the South Pole and passes through the Royal Observatory in Greenwich, which is in Greenwich, England. Because it passes through Greenwich, that line is commonly known as the Greenwich meridian.

Historically, different countries used different reference meridians, but in 1884 the international community agreed to Greenwich as the standard. The other cities listed—Paris, Rome, and Cairo—are not on the 0-degree line, so they are not the basis for the Prime Meridian.