Final answer:
To protect CUI, encryption, Multi-Factor Authentication, and security audits are correct measures, but public posting is not a safe practice.
Step-by-step explanation:
The correct way to protect Controlled Unclassified Information (CUI) includes utilizing security measures such as encryption, employing Multi-Factor Authentication (MFA), and conducting Regular Security Audits. These approaches help in ensuring that access to sensitive information is controlled and monitored. However, Public Posting of CUI is not a correct way to protect it, as this would expose sensitive information to the general public, potentially leading to unauthorized access or breaches.