A company has drafted an insider-threat policy that prohibits the use of external storage devices. Which of the following would BEST protect the company from data exfiltration via removable media?


A. Monitoring large data transfer transactions in the firewall logs
B. Developing mandatory training to educate employees about the removable media policy
C. Implementing a group policy to block user access to system files
D. Blocking removable-media devices and write capabilities using a host-based security tool