What action should a system take after a user resets their password?

Logging the action and informing the user via their registered email address is essential for maintaining security and transparency. When a user resets their password, it's crucial to document this action for audit purposes and to ensure that any unauthorized attempts to reset passwords are tracked. Notifying the user via their registered email helps confirm the reset, ensuring they are aware of any changes made to their account. This is particularly important in case the password was reset without their consent, as it allows them to take appropriate action if necessary.

Automatically logging the user into their account after a reset might seem convenient, but it can pose a security risk if the reset was not initiated by the rightful account owner. Deleting the user account and requiring re-registration is an extreme measure that is not typically warranted in this scenario and could lead to loss of access to important data. Notifying the user via text message, while useful in certain contexts, may not always be an option if the user has not set up that method of communication. Thus, the first option serves the dual purpose of enhancing security and keeping the user informed.