Which AWS solution can the company use to meet this requirement?

Explanations:

AWS Storage Gateway file gateway provides file-level access to Amazon S3, but it does not support iSCSI connectivity. It is designed for applications that require file sharing and does not meet the requirement for block storage via iSCSI.

Amazon API Gateway is a service for creating and managing APIs. It does not provide connectivity for on-premises applications to AWS storage via iSCSI. This option is not relevant to storage connectivity needs.

AWS Storage Gateway volume gateway provides block storage and supports iSCSI connections, allowing on-premises applications to connect to AWS Cloud storage. This option is specifically designed for such connectivity, enabling seamless integration of on-premises environments with AWS.

AWS Transit Gateway is a networking service that connects multiple VPCs and on-premises networks. It does not provide storage capabilities or iSCSI connectivity directly, making it unsuitable for connecting applications to AWS Cloud storage.