`ABCDE` is a smooth iron track in the vertical plane. The sections `ABC` and `CDE` are quarter circles. Points `B` and `D` are very close to `C.M` is a small magnet of mass `m`. The force of attraction between `M` and the track is `F`, which is constant and always normal to the track. `M` starts from rest at `A`, then:
A. If M is not leave the track at C then `Fge2mg` .
B. At B, the normal reaction of the track is `F-2mg` .
C. At D =, the normal reaction of the track is `F+2mg` .
D. The normal reaction of the track is equal to F at some point between A and B.
