Final answer:
The layered security approach that is not appropriate for Susan to implement is MFA (Multi-Factor Authentication). Organizations generally implement other layers to protect against phishing scams and other cybersecurity threats.
Step-by-step explanation:
The layered security approach that is not appropriate for Susan to implement to protect her organization from future issues is A. MFA (Multi-Factor Authentication). Although MFA is generally considered an effective security measure, it pertains more to increasing security for individuals rather than organizations. MFA involves using multiple factors, such as passwords and biometrics, to verify the identity of a user. While it is crucial for individuals to use MFA for their accounts, organizations usually implement other layers, such as multi-tiered firewalls, awareness programs, and SIEM (Security Information and Event Management) monitoring, to protect against phishing scams and other cybersecurity threats.