Option A is incorrect because altering the project's default region does not relocate existing App Engine applications; it only affects new resources. Option B is incorrect as the default region of an existing App Engine application cannot be changed after creation. Option C, while feasible, does not meet the requirement to move the existing application, as it would create a separate application. Option D is correct because relocating an existing App Engine application to a new region requires creating a new application in the desired region within a new project, aligning with the director's request.