Explanation
Senior management support is the most important factor to have in place for an organization's information security program to be effective because it helps to establish the vision, direction, and goals of the program, as well as to allocate the necessary resources and authority to implement and maintain it. Senior management support also helps to foster a security culture within the organization, where security is seen as a shared responsibility and a business enabler. Senior management support also helps to ensure compliance with internal and external security policies and standards, as well as to communicate the value and impact of security to stakeholders. Therefore, senior management support is the correct answer.
References:
https://www.isaca.org/resources/isaca-journal/issues/2020/volume-6/key-performance-indicators-for-secur
https://www.ffiec.gov/press/PDF/FFIEC_IT_Handbook_Information_Security_Booklet.pdf
https://www.cdse.edu/Portals/124/Documents/student-guides/IF011-guide.pdf?ver=UA7IDZRN_y066rLB