The correct choice is Configuring and maintaining server-side encryption for stored data. This responsibility falls to the customer under the shared responsibility model.

Customers decide how data is protected in the cloud and they must enable and configure encryption, choose key management approaches and apply appropriate access policies. For example customers can select among server-side encryption options and decide whether to use AWS Key Management Service or manage their own keys and permissions and they must configure IAM and storage settings to enforce encryption.

Managing physical cabling and switch configurations inside AWS data centers is incorrect because AWS operates and secures the physical network infrastructure and cabling inside its data centers.

Guarding and locking server racks in AWS facilities is incorrect because physical facility security and controlled access to racks and buildings are provided by AWS.

Administering hardware firewall appliances within the AWS data center network is incorrect because AWS manages the core hardware and network appliances that support managed services and the AWS responsibility covers those components.

Full AWS Practitioner Certification Question