Which three statements about STP timers are true？（）

• A、STP timers values （hello， forward delay， max age） are included in each BPDU.
• B、A switch is not concerned about its local configuration of the STP timers values. It will only consider the value of the STP timers contained in the BPDU it is receiving.
• C、To successfully exchange BPDUs between two switches， their STP timers value （hello， forward delay， max age） must be the same.
• D、If any STP timer value （hello， forward delay， max age） needs to be changed， it should at least be changed on the root bridge and backup root bridge.
• E、On a switched network with a small network diameter， the STP hello timer can be tuned to a lower value to decrease the load on the switch CPU.
• F、The root bridge passes the timer information in BPDUs to all routers in the Layer 3 configuration.