How does time-boxing help minimize scope creep in agile projects?

Midway through a project, a project manager determined the project was running far behind schedule. If the project manager needs to shorten the project schedule without changing the project scope, which of the following schedule compression techniques could he use?

Projects operating in agile environments where a high degree of uncertainty exists and where the scope is not yet fully defined, may not benefit from detailed cost calculations due to frequent changes. Instead, lightweight estimation methods can be used to generate a fast, high-level forecast of project labor costs, which can then be easily adjusted as changes arise. Detailed estimates are:

Kevin is assigned to a software development project that will start in the near future and is currently tailoring the PMBOK processes to satisfy the project’s specific needs. Kevin wants to introduce a new process, “Identify Key Deliverables”, to the existing six project scope management processes. Although he understands that project deliverables identification is already in the PMBOK scope management processes, he believes that having a dedicated process will stress the importance of determining and agreeing to key project deliverables. The best position for the new “Identify Key Deliverables” process should be between which of the following two processes?