A multinational payment processor conducts a long-term risk assessment to evaluate the durability of its...

The correct answer is C. Encrypt stored data with quantum-resistant algorithms.

The question asks for a mitigation that directly addresses cryptographic resilience for stored data. If future quantum computers can break currently deployed public-key schemes, then the appropriate defense is to migrate protected data and key-establishment designs toward post-quantum or quantum-resistant cryptographic algorithms.

CEH cryptography material explains that cryptographic attacks attempt to recover encryption keys and that weak encryption algorithms may not be resistant enough against cryptographic attacks . In this scenario, the risk is not network exposure or poor coding practice; it is the future strength of the cryptographic algorithm itself.

Option A. Use quantum-specific firewalls is incorrect because firewalls do not protect already encrypted archives from cryptanalytic key recovery.

Option B. Break data into fragments and distribute it across multiple locations may reduce concentration risk, but it does not solve the weakness of an encryption algorithm vulnerable to quantum cryptanalysis.

Option D. Include quantum-resistance checks in SDLC and code review processes is useful as a governance practice, but it does not directly protect the stored archives unless the cryptography is actually changed.

Option C. Encrypt stored data with quantum-resistant algorithms is correct because it directly mitigates the future decryption risk.

Therefore, the best answer is C. Encrypt stored data with quantum-resistant algorithms.