Correct Answer: C
Explanation:
Web browsers rely on PKI to establish trust in secure connections, primarily through X.509 certificates and a built-in set of trusted root Certificate Authorities (CAs). When a browser connects to an HTTPS site, the server presents a certificate chain. The browser validates that chain up to a trusted root, checks that the certificate is valid for the domain (SAN/CN matching), confirms validity dates, and may check revocation status. This PKI process allows browsers to authenticate the website's identity and negotiate encrypted session keys for TLS, enabling confidentiality and integrity for the connection. In practical terms, the browser's PKI components include certificate stores, validation logic, and mechanisms for handling intermediates, trust policies, and revocation. While PKI supports authentication as an outcome, the best description of how browsers utilize PKI is that they manage and validate digital certificates and associated keys to establish trust. PKI is not about compressing messages or encrypting data at rest; it is about identity binding and trust chains that make secure web communication possible.