Final answer:
The most appropriate person to sign the incident response policy would be the Director of Security.
Step-by-step explanation:
The most appropriate person to sign the proposed incident response policy would be the Director of Security. The incident response policy is a crucial aspect of an organization's security strategy, and the Director of Security is responsible for overseeing and implementing security measures.
The CEO may have the authority to sign off on the policy, but it is more suitable for the Director of Security to do so as they are directly involved in managing security protocols.
The CIO and CSIRT Leader may play important roles in developing and enforcing the incident response policy, but they may not have the overall responsibility or authority to sign off on it.