A network engineer is deploying Cisco Catalyst SD-WAN Cloud OnRamp for Multicloud into an AWS environment. The design requires the SD-WAN cloud gateway (Catalyst 8000V instances in a transit VPC) to exchange routes dynamically with an existing AWS Transit Gateway so that branch prefixes are learned by multiple spoke VPCs, and TGW-attached VPC prefixes are advertised back into the SD-WAN overlay. Which attachment and routing mechanism should the engineer configure between the cloud gateway and the Transit Gateway to meet this requirement?