(2011?Ningbo) As shown in the figure "suspended magnetic ring" activity, assuming that the three magnetic ring A, B, C is the same, the center of the plastic tube is smooth. When the magnetic ring

B magnetic ring is subjected to downward force: vertical downward force of gravity G, A on the B force F1; upward force is only C on the B force F2.

And because the B magnetic ring is at rest belongs to the state of equilibrium, it is subjected to the combined force of zero, that is, F2 = G + F1. so F1 is less than F2.

Therefore, the choice of A!

So choose A.