You have done a partial migration from 802.1D STP to 802.1w STP. Which of the following is true？（）

• A、802.1D and 802.1w interoperate only when the 802.1D STP domain supports rapid convergence.
• B、Ports leading to 802.1D devices will run in compatibility mode， while the rest of the ports will run in 802.1w mode.
• C、This is an invalid configuration and a partial migration cannot be done.
• D、The bridge timers will be set to match the 802.1D devices.
• E、A secondary root bridge will always be populated within the 802.1D domain.
• F、If the root bridge is selected within the 802.1D domain， the whole STP domain will run in 802.1D compatibility mode.
• G、In partially migrated 802.1w networks， it is recommended to keep the STP diameter below 4.