When auditing the feasibility study of a system development project, the IS auditor should review cost-benefit documentation for reasonableness. The feasibility study should include an assessment of the costs and benefits of the proposed system and a determination of whether the benefits of the project justify its costs. The IS auditor should review the cost-benefit analysis to ensure that it is reasonable and accurately reflects the costs and benefits of the proposed system. Reference: ISACA. (2021). 2021 CISA Review Manual, 27th Edition. ISACA. (Chapter 8, Systems Development, Acquisition, and Implementation)