AWS Transit Gateway allows the SAP solutions architect to connect multiple VPCs and on-premises networks together in a scalable manner. It acts as a hub that controls how traffic is routed between the connected networks. By attaching the VPCs and the on-premises environment to the Transit Gateway, the SAP solutions architect can establish a single connection to the overlay IP address in the high availability cluster, ensuring that the cluster is accessible from all locations.

C is correct because distributing the SAP application servers equally across two Availability Zones provides system reliability by ensuring that at least three application servers are available in each Availability Zone. This meets the requirement that the SAP application availability remains greater than 60%. This will also provide an additional layer of redundancy and protection against a single point of failure. References:

Amazon Elastic Block Store (EBS) Provisioned IOPS SSD (io1) provides high IOPS, low latency, and high throughput, making it ideal for use as a storage option for SAP HANA data and log volumes. It is designed for I/O-intensive workloads and is recommended for SAP HANA. Amazon Elastic Block Store (EBS) General Purpose SSD (gp2, gp3) is also a good choice for SAP HANA data and log storage, it provides a balance of performance and cost, with a low latency and high throughput. Amazon S3 is an object storage service and not suitable for storing the SAP HANA data and log volumes. Amazon Elastic File System (Amazon EFS) is a file storage service, it's not a good fit for block-based storage workloads like SAP HANA.