Exam IIA-CIA-Part2 topic 1 question 78 discussion

A company has recently incurred significant cost overruns on one of its construction projects. Management suspects that these overruns were caused by the contractor improperly accounting for costs related to contract change orders. Which of the following procedures would be appropriate for testing this suspicion?
I. Verify that the contractor has not charged change orders with costs that have already been billed to the original contract.
II. Determine if the contractor has billed for original contract work that was canceled as a result of change orders.
III. Verify that the change orders were properly approved by management.