Which of the following this true of a rock that has the property of paleomagnetism?

A: rocks formed millions of years ago show the location of the magnetic poles at the time of their formation
B: all rocks, regardless of when they are formed, will eventually possess the same polarity
C: a major shift in polarity occurred in all rocks that were formed one million years ago
D: a rock possesses a specific polarity depending on where it is formed