What is the purpose of serving resources securely over TLS?

Serving resources securely over TLS (Transport Layer Security) primarily aims to encrypt the data transmitted between the client and server, which significantly enhances the security of that communication. Option B, which focuses on avoiding mixed content warnings, is directly related to this purpose. When a webpage is served over HTTPS (which utilizes TLS), all resources (like images, scripts, or styles) must also be served over HTTPS to avoid mixed content. Mixed content occurs when a secure page attempts to load resources over an insecure HTTP connection, which can lead to vulnerabilities and a poor user experience as modern browsers flag or block such content.

This is particularly critical for maintaining webpage integrity and user trust, as serving mixed content can allow attackers to intercept and manipulate unsecured resources. Therefore, serving all resources over HTTPS not only protects the communication integrity but also provides a seamless experience without the warnings or blocks indicative of mixed content issues.

The other options, while related to web performance and configurations, do not directly address the primary security feature and need for using TLS in ensuring a fully secure environment for users.