Of the ways listed, which is the best method to temporarily suspend a user's ability to interactively login?

`passwd -d username` removes the password, which may enable passwordless login on some systems or is generally a less secure and less explicit way to suspend an account than expiration.

Using `chage -E YYYY-MM-DD username` allows an administrator to set an expiration date for a user account, effectively preventing login until the expiration is removed or extended, providing a clean and reversible method for temporary suspension. Setting `-E 1` for today's date would immediately expire it, and `-E -1` would disable expiration.

Changing the user's password forces them to use a new password, which is a disruption and less clear than an account suspension, and requires explicit communication and resetting later.

Adding `exit` to a user's `.login` or shell startup file is a less robust and potentially fragile method, as it relies on specific shell configurations and may not prevent all forms of interactive access.