Which of the following is considered the best way to protect Personally Identifiable Information (PII) from Web application vulnerabilities?

Cryptographic storage protects PII at rest inside databases or file systems, but does not address the exposure of that data while it is actively transmitted over the network through a web application.

Encrypted communications protocols like TLS/HTTPS protect PII as it travels between the client and server, preventing interception through attacks such as man-in-the-middle and passive eavesdropping - risks directly associated with web application vulnerabilities. OWASP identifies insecure data transmission as a core risk under Sensitive Data Exposure, and enforcing HTTPS is the foundational baseline control for protecting PII in any web application.

Full disk encryption protects data stored on physical media from unauthorized physical access, but provides no protection against PII exposed during network transmission or web application processing.

Security tokens strengthen authentication and reduce unauthorized login risk, but they do not prevent PII from being exposed through transmission-layer vulnerabilities once a session is established.