Which of the following is an important line of longitude?

Step 1: Analyze the question The question asks which option is a line of longitude. Each option is either a line of latitude or a line of longitude, so we need to tell them apart.

Step 2: Explain the concept

• Lines of latitude (parallels) run east-west, parallel to the Equator. They measure distance north or south of the Equator.
• Lines of longitude (meridians) run north-south from pole to pole. They measure distance east or west of the Prime Meridian (0°).

Step 3: Check each option

• A. Antarctic Circle is a line of latitude at about 66½°S.
• B. Arctic Circle is a line of latitude at about 66½°N.
• C. Prime Meridian is a line of longitude at 0°, passing through Greenwich, London. It is the reference line for measuring longitude, and it also passes through Ghana.
• D. Tropic of Cancer is a line of latitude at about 23½°N.

Step 4: Answer Only the Prime Meridian is a line of longitude.

Tip: Latitude lines are like the rungs of a ladder, running side to side, so "lat" sounds like "ladder." Any line named a "Circle" or a "Tropic" (Arctic, Antarctic, Cancer, Capricorn) is latitude. The word "Meridian" always means longitude.