Comprehensive and Detailed Explanation
Cloud interconnects that support BGP peering must provide a routed Layer-3 adjacency capable of exchanging routing information dynamically. In major cloud architectures:
AWS Direct Connect supports private virtual interfaces (VIFs) where BGP is used between the customer router and AWS to exchange routes.
Azure S2S VPN uses IPsec tunnels with static routing by default; BGP is optional only with specific gateway SKUs, but the question expects the standard, universally correct answer, which is Direct Connect.
Azure Bastion is a remote-access management service and does not support BGP.
AWS-managed VPN uses IPsec tunnels with BGP optional, but in exams, the recognized cloud service specifically associated with BGP support is Direct Connect.
In service provider cloud interconnect design, AWS Direct Connect is the standard, well-defined offering that provides layerized WAN connectivity with BGP support.