A transit gateway is connects virtual private cloud and on-premises networks through a central hub. East-West traffic is defined as traffic that goes between VPCs. VPC traffic does not traverse a a transit gateway. A centralized model is a model that utilizes transit gateways. All this info is pulled from the aws transit gateway deployment guide. I think the Answer is B

The design models presented here differ in how they provide resiliency, scale, and services for the design. The design models in this reference design are: • Centralized—Supports interconnecting a large number of VPCs, with a scalable solution to secure outbound, inbound, and east-west traffic flows using a transit gateway to connect the VPCs. • Isolated—Supports outbound and inbound traffic flows. This design model does not support east-west traffic flows between VPCs. This design is useful for regional security where one or more isolated VPCs need protection.

https://www.paloaltonetworks.com/apps/pan/public/downloadResource?pagePath=/content/pan/en_US/resources/guides/aws-transit-gateway-deployment-guide

Correct Answer: A Provides deployment details for the Centralized design model, which scales enterprise cloud deployments. This guide describes deploying VM-Series firewalls to provide resilient visibility and protection for the subscriber virtual private cloud’s (VPC’s) inbound, east-west, and outbound traffic using the AWS transit gateway and Gateway Load Balancer. https://www.paloaltonetworks.com/apps/pan/public/downloadResource?pagePath=/content/pan/en_US/resources/guides/aws-transit-gateway-deployment-guide