What is the Naval Communications Security Material System abbreviated as?

The Naval Communications Security Material System is correctly abbreviated as NCMS. This system is integral to the management and dissemination of communication security materials within the U.S. Navy and functions to ensure that secure communications are maintained through the proper handling of classified materials.

While the other options represent different terms or acronyms related to communications security or similar areas, they do not specifically refer to the Naval Communications Security Material System. COMSEC, for instance, stands for communications security more broadly and encompasses a range of measures for securing communication information. EKS is typically associated with encryption key management systems, and PKI stands for public key infrastructure, which involves the management of digital certificates for secure communications. However, NCMS is specifically focused on the Navy's procedures and policies regarding secure communications materials.