The table highlights that tampering threats (IDs 02 and 03) are rated Critical, making them the most significant risks. These threats involve malicious insiders inserting backdoors or attackers injecting malicious code into third-party libraries. To mitigate such risks, organizations must implement a secure software development lifecycle (SDLC) with formalized code scanning, gate checks, and supply chain validation.

Option C directly addresses these issues. Secure development practices include static/dynamic code analysis, dependency checks, peer reviews, and mandatory approvals before code promotion. This approach detects backdoors, prevents unauthorized modifications, and reduces the likelihood of compromised libraries being integrated.

Option A (PAM with conditional access) mitigates privilege escalation but does not address software tampering. Option B (rate limiting and federation) reduces brute-force authentication risks (ID 05) but not critical tampering. Option D (Zero Trust with microsegmentation) strengthens network defense but does not secure the integrity of source code or libraries.

Therefore, a secure SDLC with gate checks and code scanning is the best mitigation for the most critical threats identified.