According to the PMBOK® Guide, Validate Scope is the process of formalizing acceptance of the completed project deliverables. This process is primarily concerned with the customer or sponsor ' s acceptance of the work that has been performed.

Key Inputs: The most critical input for this process is Verified Deliverables. These are deliverables that have already been internally inspected and confirmed to be correct through the Control Quality process.

Process Flow:

The project team completes a deliverable.

Control Quality (Internal) happens first to ensure the deliverable is " correct " and meets technical specifications.

Validate Scope (External/Sponsor) follows, where the customer reviews the work to ensure it meets their requirements.

Key Output: The primary output of this process is Accepted Deliverables. These are formally signed off by the customer or sponsor. If a deliverable is not accepted, change requests are generated to bring the deliverable into alignment with the requirements.

Comparison with other options:

B. Close Project or Phase: This is the process of finalizing all activities for the project, phase, or contract. While it involves checking that all scope was completed, the specific act of formalizing acceptance for individual deliverables occurs in Validate Scope.

C. Control Quality: This process is concerned with the correctness of the deliverables and meeting the quality requirements. It is an internal process performed by the project team, whereas Validate Scope is focused on acceptance by the customer.

D. Verify Scope: This was the name of the process in older versions of the PMBOK® Guide (4th Edition and earlier). In modern PMI standards (5th Edition onwards), this process was renamed to Validate Scope to better reflect its purpose of gaining formal validation/acceptance from stakeholders.