Answer:
A. Multifactor authentication
Step-by-step explanation:
Multifactor authentication is a security system process that requires a user to verify his or her identity by providing two categories of credentials.
A mobile device user has entered her user ID and password to access an online account, she immediately receives a text message with a unique PIN or One Time Password (OTP) that must be entered before she is granted access to the account. This is an example of a multifactor authentication security method.