"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. "

From the Prime Meridian to the east, longitude will increase until the opposite side of the planet from the Prime Meridian (at most locations the International Date Line) which would be 180°E.Longitude would begin decreasing, and it would change direction, from East to West. Lines of longitude circle the Earth in one place. There aren't two lines of longitude of 180, only one. There is no reason to designate it being east or west of something because there is only one line, not two.