The answer to this is A. You should stop 3 meters away because you have to be sure that there are no cars that will suddenly appear. This should be done for your safety. If you would do B, you will not be able to do anything when a car that is rushing will go towards you.
C is also not advisable because stopping suddenly may have an effect on the other cars that are behind you. You should not stop only for pedestrians because there are other reasons why you should stop or at least a slowdown. By being more careful, you can help prevent accidents now and in the future.