Which one of the followinglongitudes alongwith the primeMeridian forms a great circle on theglobe? [UPPCS (Pre) 2000](A) 0º (B) 90º E(C) 90º W (D) 180º

The answer is (D) 180º.

Here's why:

A great circle on the globe is formed by any plane that cuts the globe into two equal halves. The plane must pass through the center of the globe.

The Prime Meridian (0º) and the 180º longitude line together form a great circle. This is because the 180º line is on the exact opposite side of the globe from the Prime Meridian, so a plane passing through these two lines would cut the globe into two equal halves.

The 90º E and 90º W lines would not form a great circle with the Prime Meridian because they are not on the exact opposite side of the globe from the Prime Meridian. A plane passing through these lines would not cut the globe into two equal halves.