Which of the following represents a constructive change to an existing contract?

Instead of using the contractor's maintenance contract, the Government facilities manager takes a laptop to a local repair shop because he does not have time to complete the appropriate maintenance request forms.

The Program Manager authorizes the contractor to begin work on a new task before the CO officially executes the task order

The contractor delivers supplies that meet contract requirements. However the COR sees opportunities for improvements that will better meet the Government's needs , and therefore sends the items back for corrections.