In the AWS shared responsibility model, the customer is responsible for the security 'in' the cloud, while AWS is responsible for the security 'of' the cloud. For Amazon EC2 instances, which is option B, customers are responsible for managing the guest operating system, including applying the latest security updates and patches. In contrast, AWS manages the underlying infrastructure, including the host operating system, virtualization layer, and physical security of the data centers. Options A, C, and D are managed services where AWS handles the underlying infrastructure and security, so customers do not need to apply updates and patches for these services.