Ann, a user, is attempting to log in to her email service form a third-party email client on her phone. When Ann enters her usual username and password, she receives an error message saying the credentials are invalid. Ann then decides to reset her email password, but after the reset, the new credentials still do not work in the third-party email client. Which of the following settings or features is responsible for the problems Ann is experiencing?
A. Full device encryption
B. Account lock
C. Multifactor authentication
D. Strong password requirements