Which two statements are correct regarding Flex Links? (Choose two.)

A.
An interface can belong to multiple Flex Links

B.
Flex Links operate only over single pairs of links

C.
Flex Link pairs must be of the same interface type

D.
Flex Links automatically disable STP so no BPDUs are propagated

E.
Failover from active to standby on Flex Links takes less than a second.

Explanation:
Flex Links are a pair of a Layer 2 interfaces (ports or port channels), where one interface is configured to act as a backup to the other. Flex Links are typically
configured in service-provider or enterprise networks where customers do not want to run STP. Flex Links provide link-level redundancy that is an alternative to
Spanning Tree Protocol (STP). STP is automatically disabled on Flex Links interfaces.
A backup link does not have to be the same type as the active link.
To configure the Flex Links feature, you configure one Layer 2 interface as the standby link for the link that you want to be primary. With Flex Links configured for a
pair of interfaces, only one of the interfaces is in the linkup state and is forwarding traffic. If the primary link shuts down, the standby link starts forwarding traffic.
When the inactive link comes back up, it goes into standby mode.
https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst6500/ios/12-2SX/configuration/guide/book/flexlink.html