Jack Has Not Logged in to His E-Mail Account for a Couple

Multiple Choice

Jack has not logged in to his e-mail account for a couple of weeks. Now, after entering his name and password, he receives an error message indicating that the username or password is invalid. What can he infer from this error message?

A) The physical layer is working.
B) Username and password are correct.
C) The network is suffering from traffic congestion.
D) The central router is down.