Answer:
The correct option for the given question option(B).i.e Information about the existence of a user.
Step-by-step explanation:
The insecure login system provide the insecurity they are not reliable they provide information and data about the of an existence user .they do not provide the user privileges and password information even they do not provide the information about complexity of the password .After logging on these login system they provide Information about existence of a user.
so the correct option is (B)