Answer : 2. "Milestone"
Explanation :

Answer: B) Milestone Explanation: 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.