A geographic compass is used to tell the direction you are facing on the Earth. A compass has a movable needle in it that is a magnet with the north pole painted red. Where that red needle points is the direction north on the Earth. The needle moves because it interacts with the magnetic field of the Earth. Which of the following statements is the most true?
a The needle must be a magnet with only one pole
b The direction the needle points north switches when you change hemispheres
c The geographic North Pole of the Earth is actually the magnetic South Pole
d There must a current running through the compass needle for it to work