1) Validate Scope is done multiple times throughout the project with the customer.This is actually formal acceptance of PROJECT SCOPE.Project scope is verified against the scope baseline/P.M.P

Product verification or formal acceptance of PRODUCT OF PROJECT is done in the closing phase.It is normally done once for phase/project.Product scope is done against the product requirements.

The question is Validate Scope is done to meet ------------
- Product Acceptance Criteria
- Project Acceptance Criteria