Which two RSTP port roles include the port as part of the active topology? (Choose two.)

A.
root

B.
designated

C.
alternate

D.
backup

E.
forwarding

F.
learning

Explanation:
RSTP defines four port roles:
+ Root port
+ Designated port
+ Alternate port
+ Backup port and three port states:
+ Discarding
+ Learning
+ Forwarding
Only the root ports and designated ports belong to the active STP topology.
Reference:
http://www.cisco.com/en/US/tech/tk389/tk621/technologies_white_paper09186a0080094cfa.shtml