For a large-scale multi-account AWS environment with many VPCs and centralized Direct Connect, AWS recommends using a Transit Gateway (TGW) architecture combined with a Direct Connect gateway (DXGW). This setup allows scalable, centralized connectivity between on-premises and multiple VPCs across accounts.

Step B: Creating a Direct Connect gateway and Transit Gateway in a central network account and connecting them via a transit VIF enables the on-premises network to access all connected VPCs.

Step D: Sharing the transit gateway with other accounts via AWS Resource Access Manager (RAM) allows the central TGW to attach VPCs in multiple accounts, simplifying multi-account connectivity.

Step F: To route cloud resources’ internet traffic back through the on-premises data center (for centralized egress), provisioning only private subnets and routing outbound internet traffic through NAT or firewall services in the data center is necessary. This requires configuring transit gateway and customer gateway routes appropriately.

Option A is partially correct in the use of Direct Connect gateway but association proposals are not scalable for hundreds of VPCs and accounts compared to transit gateway. Option C (internet gateway) is irrelevant here as traffic egress is required via on-premises data center, not directly to the internet. Option E (VPC peering) is not scalable for hundreds of VPCs.