Which of the following is the BEST use case for client-side virtualization?

Client-side virtualization excels at creating isolated environments on a desktop or laptop to run applications that are incompatible with the host operating system, such as legacy software requiring older Windows versions. This allows businesses to continue using critical but outdated applications without migrating the entire operating system or hardware.

Email clients are typically run directly on the host operating system or accessed via web browsers, and do not inherently require client-side virtualization for operation.

Directory services (like Active Directory) are server-side roles, not client-side applications, and are not a use case for client-side virtualization.

Databases are typically hosted on dedicated servers, either physical or virtualized server-side, and are not a primary use case for client-side virtualization for their operation.