Which two of these statements regarding RSTP are correct?

Which two of these statements regarding RSTP are correct? (Choose two.)

A.
RSTP cannot operate with PVST+.

B.
RSTP defines new port roles.

C.
RSTP defines no new port states.

D.
RSTP is a proprietary implementation of IEEE 802.1D STP.

E.
RSTP is compatible with the original IEEE 802.1D STP.

Explanation:
http://www.cisco.com/en/US/tech/tk389/tk621/technologies_white_paper09186a0080094cfa.shtm
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Port Roles The role is now a variable assigned to a given port. The root port and designated port
roles remain, while the blocking port role is split into the backup and alternate port roles. The
Spanning Tree Algorithm (STA) determines the role of a port based on Bridge Protocol Data Units
(BPDUs). In order to simplify matters, the thing to remember about a BPDU is there is always a
method to compare any two of them and decide whether one is more useful than the other. This is
based on the value stored in the BPDU and occasionally on the port on which they are received. This
considered, the information in this section explains practical approaches to port roles.
Compatibility with 802.1D RSTP is able to interoperate with legacy STP protocols. However, it is
important to note that the inherent fast convergence benefits of 802.1w are lost when it interacts
with legacy bridges.