Which statement correctly describes the Cisco implementation of RSTP?

Which statement correctly describes the Cisco implementation of RSTP?

A.
PortFast, UplinkFast, and BackboneFast specific configurations are ignored in Rapid PVST mode

B.
RSTP is enabled globally and uses existing STP configuration

C.
Root and alternative ports transition immediatelyto the forward state

D.
Convergence is improved by using subsecond timersfor the blocking, listening, and forwarding port states