The option that is a customer responsibility under the AWS shared responsibility model is B. Application data security.

According to the AWS shared responsibility model, AWS is responsible for the security of the cloud, while the customer is responsible for the security in the cloud.This means that AWS manages the security of the underlying infrastructure, such as the hardware, software, networking, and facilities that run the AWS services, while the customer manages the security of their applications, data, and resources that they use on top of AWS12.

Application data security is one of the customer responsibilities under the AWS shared responsibility model. This means that the customer is responsible for protecting their application data from unauthorized access, modification, deletion, or leakage.The customer can use various AWS services and features to help withapplication data security, such as encryption, key management, access control, logging, and auditing12.

Maintenance of underlying hardware of Amazon EC2 instances is not a customer responsibility under the AWS shared responsibility model. This is part of the AWS responsibility to secure the cloud.AWS manages the physical servers that host the Amazon EC2 instances and ensures that they are updated, patched, and replaced as needed13.

Physical security of data centers is not a customer responsibility under the AWS shared responsibility model. This is also part of the AWS responsibility to secure the cloud.AWS operates and controls the facilities where the AWS services are hosted and ensures that they are protected from unauthorized access, environmental hazards, fire, and theft14.

Maintenance of VPC components is not a customer responsibility under the AWS shared responsibility model. This is a shared responsibility between AWS and the customer.AWS provides the VPC service and ensures that it is secure and reliable, while the customer configures and manages their own VPCs and related components,such as subnets, route tables, security groups, network ACLs, gateways, and endpoints15.