Comprehensive and Detailed Explanation:

The CMMC Assessment Process (CAP) mandates that the OSC provide initial objective evidence, including the SSP, to the Lead Assessor during the scope validation phase (Phase 1). The SSP is critical for defining the assessment scope and verifying asset categorization and security controls, as per practice CA.L2-3.12.4. Refusal or redaction (Options A and C) undermines the assessor’s ability to validate the scope, and there is no provision delaying this until after the assessment begins (Option B). The OSC must furnish the full SSP, though proprietary concerns can be addressed via an NDA if needed, which is not mentioned here.