Which of the following statements best explains the Maginot Line?
a) The Maginot Line was the defense system China used against the Japanese.
b) The Maginot Line was a line of concrete fortifications set up by the French to prevent the Germans from invading.
c) The Maginot Line was the secret defense system built by the Germans to protect themselves against the Russians.
d) The Maginot Line was the demilitarized zone between Germany and France.