A merchant acquirer has the need to store credit card numbers in a transactional database in a high performance environment. Which of the following BEST protects the credit card data?

Database field-level encryption encrypts individual columns such as credit card numbers directly within the database engine. This approach satisfies PCI DSS data protection requirements for cardholder data while allowing the database to remain performant on non-sensitive fields, since queries against unencrypted columns are unaffected and only the sensitive values are encrypted or decrypted on access.

File-level encryption encrypts entire files or tablespace files on disk, which does not protect individual records from users or applications that have legitimate access to open and query the database files.

A data loss prevention system monitors and restricts data movement and egress but does not encrypt stored data, leaving the credit card numbers unprotected at rest.

Full disk encryption protects data if physical media is stolen but provides no protection against logical access by authorized database users or compromised application accounts.