Which of the following is the BEST way to protect Personally Identifiable Information (PII) from being exploited due to vulnerabilities of varying web applications?

Cryptographic storage protects PII at rest on the server, but does not safeguard data during transmission where network-level exploitation of web application vulnerabilities can expose it.

Full disk encryption protects data stored on physical media from theft or loss, but does not address vulnerabilities in web applications that expose PII over the network.

Using encrypted communication protocols such as TLS/HTTPS ensures that PII is protected while traversing the network, which is the most exposed point when web application vulnerabilities are exploited by attackers intercepting or manipulating traffic. This directly addresses the OWASP Sensitive Data Exposure risk by ensuring that even if an application has weaknesses, data in transit remains confidential and cannot be read in cleartext.

A security token strengthens user authentication, but once a session is established, it does not protect PII from being exposed through application-layer vulnerabilities or insecure transmission.