The approval by the Architecture Review Board is a milestone you want to include in activity sequencing so that you can ensure the requirements for meeting the review board's approval are met.  Answer A is tempting because the question references phase-end activities; however, it is not an example of gatekeeping because the project is not being authorized to continue based only on the architecture review.Gatekeeping often involves the review of other factors as well. Answer C is incorect because the requirement of a review board approval does not afect scope. Answer D is incorrect because project integration planning involves project plan development, execution, and integrated change control, which are not related to a review board.

Life Cycle costing includes the costs from each phase of the project life cycle when the total investment costs are calculated. Answer A is incorrect because an opportunity cost is the difference between a chosen investment and the one that is passed up. Answer B is incorrect because sunk costs are costs that have been incurred and cannot be reversed. Answer C is incorrect because net present value (NPV) is the present value of cash inflows(benifits) minus the present value of cash outflows (costs).

The project details and description will usually have less detail at the beginning of the project and will increase as the characteristics are progressively elaborated. Answer A is incorrect because the team should confirm that they understand the esence of the scope of the project, even if the details might be ambiguous at the beginning of the project. Answer B is incorrect because the project should go forward; however, the team should request further clarification of what the project scope entails. Answer D is incorrect because the project selection criteria should be established before the project begins.

Project authorization should not be exclusively based upon the impact of an executive's bonus (many people would agree that it should not ever be based upon an executive's bonus). Answer A, B, and D are common events that predicate the need for project authorization and can evolve into large scope projects.

Answer D is correct because a sunk cost is a project expense that will eventualy need to be paid. Answer A is incorrect because a fixed cost remains constant, regardless of any change in a company's activity. Answer B is incorrect because direct cost can be directly linked to producing specific goods or services. Answer C is incorrect because a variable cost changes in proportion to a change in the company's activity or business.

The payback period is how long it takes to recoup your investment. In this example, the cost was $4,000,000 and the savings was $800,000 per year. $4,000,000/$800,000 = 5. Therefore, Answer A, B and D are incorrect.