Answer:
A. The client received a fake security alert.
Step-by-step explanation:
A fake security alert are fake error messages that used as a social engineering to display messages that will not go away. The aim of this fake error message is to trick the user into calling an indicated technical support hotline.
What has happened to this customer in this case is a fake security alert and should never call the phone number. The aim of the five minutes deadline is to trick the user to think that the case is very urgent so that the customer will rush to call the number.