The Antarctic Circle is located in the (b) Southern Hemisphere.

Here are the answers to the questions:

1. The Antarctic Circle is located in the (b) Southern Hemisphere. The Antarctic Circle is one of the five major circles of latitude that mark maps of the Earth, located in the Southern Hemisphere.

2. Equator : $0^\circ$, North Pole : $90^\circ$N, South Pole : (a) $90^\circ$S. The South Pole is the southernmost point on Earth, located at $90^\circ$ South latitude.