Answer - B
The AWS documentation mentions the following on BFD
Bidirectional Forwarding Detection (BFD) is a network fault detection protocol that provides fast failure detection times, which facilitates faster re-convergence time for dynamic routing protocols. It is independent of media, routing protocol, and data. We recommend enabling BFD when configuring multiple AWS Direct Connect connections or when configuring a single AWS Direct Connect connection and a VPN connection as a back up to ensure fast detection and failover. You can configure BFD to detect link or path failures and update dynamic routing as Direct Connect quickly terminates BGP peering so that backup routes can kick in. This ensures that the Bidirectional Forwarding Detection (BGP) neighbor relationship is quickly torn down instead of waiting for 3 keep-alives to fail at a hold-down time of 90sec.
For more information on Bidirectional Forwarding Detection, please visit the below URL:
https://aws.amazon.com/premiumsupport/knowledge-center/enable-bfd-direct-connect/