Which service is described as a secure enterprise storage and sharing solution?

Amazon WorkDocs is designed specifically as a secure enterprise storage and sharing solution, enabling users to create, store, and collaborate on documents and files easily. It includes features such as real-time collaboration, version control, and secure file sharing, making it particularly useful for organizations that need a safe and efficient way to manage their documents. The service emphasizes security, compliance, and ease of access from various devices, which are crucial for enterprise environments.

In contrast, Amazon WorkMail is primarily an email and calendaring service; Amazon WorkSpaces provides virtual desktop infrastructure to allow users to access a consistent workspace from anywhere; and Amazon AppStream 2.0 is a fully managed application streaming service that allows users to stream desktop applications from AWS to any device. Each of these services serves different purposes and does not focus on file storage and sharing in the same way WorkDocs does, highlighting why the latter is the correct answer for this question.