Match each option to the protocol that actually owns it. Email is SMTP, name-to-address lookup is DNS, and secure file transfer is SFTP or FTPS. That leaves web page delivery for HTTP.
HTTP works as a simple request and response exchange:
\[ \text{Browser (GET)} \longrightarrow \text{Server} \longrightarrow \text{Response (web page)} \]
The browser asks for a resource, the server sends it back, and the page renders. That request-response cycle for hypertext is the essence of browsing the web.
\[\boxed{\text{Browsing web pages}}\]