The correct answer is B because ensuring the environmental safety and security of the AWS infrastructure that hosts Workspaces is the responsibility of AWS, according to the AWS shared responsibility model. The AWS shared responsibility model is a framework that defines the division of responsibilities between AWS and the customer for security and compliance. AWS is responsible for the security of the cloud, which includes the global infrastructure, such as the regions, availability zones, and edge locations; the hardware, software, networking, and facilities that run the AWS services; and the virtualization layer that separates the customer instances and storage. The customer is responsible for the security in the cloud, which includes the customer data, the guest operating systems, the applications, the identity and access management, the firewall configuration, and the encryption. The other options are incorrect because they are the responsibility of the customer, according to the AWS shared responsibility model. Setting up multi-factor authentication (MFA) for each Workspaces user account, providing security for Workspaces user accounts through AWS Identity and Access Management (IAM), configuring AWS CloudTrail to log API calls and user activity, and encrypting data at rest and in transit are all tasks that the customer has to perform to secure their Workspaces environment. Reference: AWS Shared Responsibility Model, Amazon WorkSpaces Security