Answer:
a. social engineering attack
Explanation:
Two-factor authentication requires that the user/owner of the account enter a second verification code alongside their password in order to access the account. This code is usually sent to a personal phone number or email address. Therefore in order to breach such a security measure the best options is a social engineering attack. These are attacks that are accomplished through human interactions, using psychological manipulation in order to trick the victim into making a mistake or giving away that private information such as the verification code or access to the private email.
