Which of the following allows values to be shared between all user sessions and never expires?

The correct choice relates to cross-session (site) properties, which are designed specifically for shared values across all user sessions. Unlike session variables, which are unique to each user session and are discarded when the session ends, cross-session properties persist beyond individual user sessions. They are particularly useful for storing application-wide settings or configuration values that all users can access at any time without any expiration related to user sessions.

This means that once a value is set in a cross-session property, it remains available for all users, regardless of how many user sessions there are and whether those sessions are active or not. This property is essential for maintaining consistent states or configurations that should be uniform across the entire application.

Session variables are limited to specific user sessions, user variables are tied to individual users and their context, while function variables are temporary and only exist during the execution of a function. These other options don't facilitate the persistent sharing of values across all user sessions in the manner that cross-session properties do.