Final answer:
When a member has been idle on a page for 20+ minutes, the session times out, and they need to log in again. This is a common security measure implemented by websites to protect user accounts from unauthorized access.
Step-by-step explanation:
When a member has been idle on a page for 20+ minutes, the session times out, and they need to log in again (option a). This is a common security measure implemented by websites to protect user accounts from unauthorized access. When the session times out, it means that the server terminates the connection with the user's browser, and the user is required to enter their credentials again to continue using the website.