The correct answer is: A. International Date Line
The International Date Line is an imaginary line on the Earth’s surface that runs from the North Pole to the South Pole and separates two calendar days. It zigzags around the Earth’s surface, mostly following the 180th meridian. When you cross the International Date Line going east, you lose a day; when you cross it going west, you gain a day.
The Tropic of Cancer is an imaginary line that circles the Earth at 23.5 degrees north latitude. It marks the northernmost latitude at which the Sun can be directly overhead at noon.
The Equator is an imaginary line that circles the Earth at 0 degrees latitude. It divides the Earth into the Northern Hemisphere and the Southern Hemisphere.
The Prime Meridian is an imaginary line that runs from the North Pole to the South Pole and passes through Greenwich, England. It is the line that is used to determine time zones around the world.