A. IEEE 802.1D and IEEE 802.1w are incompatible. All three switches must use the same  standard or no traffic will pass between any of the switches.
B. Switches S1， S2， and S3 will be able to pass traffic between themselves.
C. Switches S1， S2， and S3 will be able to pass traffic between themselves. However， if there is a  topology change， Switch S2 will not receive notification of the change.
D. Switches S1 and S3 will be able to exchange traffic but neither will be able to exchange traffic  with Switch S2