The next thing that an information security manager should do after creating a roadmap to execute the strategy for an information security program is D. Develop a project plan to implement the strategy. This is because a project plan is a detailed document that outlines the scope, objectives, deliverables, milestones, tasks, resources, roles, responsibilities, risks, and dependencies of the implementation process. A project plan can help the information security manager to organize, coordinate, monitor, and control the activities and resources required to execute the strategy and achieve the desired outcomes. A project plan can also facilitate communication, collaboration, and reporting among the project team, stakeholders, and sponsors.
A project plan is a detailed document that outlines the scope, objectives, deliverables, milestones, tasks, resources, roles, responsibilities, risks, and dependencies of the implementation process. (From CISM Manual or related resources)
References = CISM Review Manual 15th Edition, Chapter 3, Section 3.1.2, page 1281; CISM Review Questions, Answers & Explanations Manual 9th Edition, Question 74, page 19