"Longitudes are imaginary lines that are drawn from North to South and run East to West on the Earth. Each degree is equivalent to 4 minutes. The Sunlight reaches the places on each longitude 4 minutes apart. Any two places on the same longitude will have the same Standard time, see the Sun at the same place in the sky. Important Points 180 Degree longitude is also called Anti Meridian and is used as the International Dateline separating two time zones of the Earth.  The international date line serves as the line of demarcation between two consecutive calendar dates. The international dateline, established in 1884, passes through the mid-Pacific Ocean and roughly follows a 180 degrees longitude north-south line on the Earth. The Equator is the 0-degree Latitude (and is not a Longitude) that is an imaginary line drawn from East to West and running North to South which cuts the Earth into two equal hemispheres.  Therefore, the answer is option 2. International Date Line.  Additional Information The other important Longitude is the Prime Meridian passes through Greenwich, London at 0-degree Longitude. Places to the East of it add 4 minutes with each passing degree while places to its West subtract 4 minutes with each passing degree to calculate the time difference with Greenwich which is at 0-degree longitude. "

360 degrees in a circle. start at Null Island 0° Latitude 0° Longitude (south of the bulge of West Africa). Go 90 degrees westwards along the Equator. You are 1/4 of the way around the world (and are near the Galapagos off the west coast of South America). Go another 90 degrees westwards. Now you're in the middle of empty ocean, in the Polynesian Triangle, crossing the 180th Meridian. Go another 90 degrees westards, and now you're at 90° East, in the Indian Ocean. 90 more degrees takes you back where you started. You've gone the full 360 degrees around the earth, east-to-west. 180 degrees east, 180 degrees west. Now let's go north from Null Island. 90 degrees northwards takes you to the North Pole, passing through Africa and western Europe along the way. But you've now got to go around the other side; you won't be on the Prime Meridian anymore; now we're tracing the 180th meridian. Take that 90 degrees, and you're back at 0, 180 in the Polynesian Triangle. 90 more takes you to 90° South, the South Pole, and the last 90 degrees swings you up through Antarctica and the South Atlantic to get back to Null Island. In both cases, a trip of 360 degrees takes you all the way around the Earth and back to where you started.