The correct answer is D because CMMC Level 1 is based on the basic safeguarding requirements in FAR Clause 52.204-21 , not on the full NIST SP 800-171 or DFARS 252.204-7012 requirements. The official CMMC Model Overview states that Level 1 focuses on protecting Federal Contract Information (FCI) and consists of security requirements that correspond to the basic safeguarding requirements specified in 48 CFR 52.204-21 , commonly referred to as the FAR Clause. It also states that Level 2 is the level that incorporates the 110 security requirements from NIST SP 800-171 Rev. 2 for protection of Controlled Unclassified Information (CUI) .

FAR 52.204-21 applies to covered contractor information systems that process, store, or transmit Federal Contract Information. The clause requires contractors to apply basic safeguarding requirements and procedures, including limiting system access to authorized users, controlling external connections, protecting information on publicly accessible systems, identifying and authenticating users, and sanitizing or destroying media containing FCI before disposal or reuse.

Option A is incorrect because NIST SP 800-171 is associated with CMMC Level 2, not Level 1. Option B is incorrect because the cited DFARS clause number is not the CMMC Level 1 source. Option C is incorrect because DFARS 252.204-7012 is tied to safeguarding covered defense information and implementing NIST SP 800-171 for CUI, not the Level 1 basic safeguarding baseline.