Which one of the following is known as the Great Circle?

A great circle is defined as any circle that divides the Earth into two equal halves or hemispheres and represents the largest circle that can be drawn on a sphere [t3][t6]. Among the parallels of latitude, the Equator (0°) is the only great circle because it passes through the center of the Earth and has the maximum length [c2][c4]. All other parallels of latitude, such as the Tropic of Cancer (23.5° N), the Tropic of Capricorn (23.5° S), and the Arctic Circle (66.5° N), are considered 'small circles' because their circumferences decrease as they move toward the poles [c3][t2][t7]. While all meridians of longitude (when paired with their opposite meridian) form great circles, the Equator remains the unique great circle among the horizontal parallels [c4][t3].

Sources

1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 18: Latitudes and Longitudes > 18.3. Comparison: Latitude vs. Longitude > p. 250
2. [2] Exploring Society:India and Beyond. Social Science-Class VI . NCERT(Revised ed 2025) > Chapter 1: Locating Places on the Earth > b) Latitudes > p. 14
3. [3] Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 2: The Earth's Crust > Great Circle Routes > p. 14