A file server on the network stores sensitive data for multiple departments in the company. A systems administrator has been instructed to ensure only data stored by the accounting department is…

Disk-level encryption encrypts all data on the entire disk or volume, making it impossible to encrypt only the accounting department's data without also encrypting all other departments' data.

File-level encryption targets individual files or directories, making it possible to encrypt only the accounting department's data on a shared file server. This is the most efficient solution because it applies encryption selectively without requiring full-disk re-encryption or user intervention, and can be enforced via access control policies such as Windows EFS (Encrypting File System).

Data transfer encryption such as TLS protects data in transit over the network, not data stored at rest on the file server.

User-initiated encryption is inefficient and unreliable because it depends on individual users to manually encrypt files, which is not a scalable or enforceable administrative solution.