The correct answer is A.
OBJ-3.2.3: Project assurance must be independent of the project manager and project support. Project assurance is the responsibility of the project board. The executive and the user representative are both members of the project board, therefore they can be combined with the role of project assurance. The project board’s responsibilities to assure itself that the project is being conducted correctly. The project board members each have a specific area of focus for project assurance, namely business assurance for the executive, user assurance for the user representative(s), and supplier assurance for the supplier representative(s).