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Question:

Which of the following settings or features is responsible for the problems: Ann, a user, is using a third-party email service on her phone to log into her email service. Ann receives an error message stating that her login and password are invalid when she inputs them. Ann then chooses to change her email password, however, the new credentials do not work in the third-party email customer following the reset. 

A Multifactor authentication
Explaination