Answer B,C is correct: B. Enabled interfaces come up and move to the forwarding state immediately; C.
Enabled interfaces never generate topology change notifications.. PortFast lets an access interface bypass the normal listening and learning delays and move directly to forwarding when the link comes up. That is valuable for end-user ports because DHCP, login scripts, and endpoint connectivity can fail or delay while classic STP converges. PortFast-enabled edge ports also do not create the same topology-change behavior expected from ordinary switch-to-switch links when end devices connect or disconnect. Cisco CCNA 200-301 v1.1 Network Access expects engineers to apply PortFast only to ports facing end hosts, not to ports that may create Layer 2 loops. The options saying the port is placed in listening state or waits 50 seconds are the opposite of PortFast behavior. The two correct benefits are immediate forwarding and avoiding unnecessary topology-change effects for edge connections.