The best answer is A.
A feasibility study that supports a business case should primarily establish whether the proposed investment is worthwhile. ISACA guidance around practical risk and project/program initiation emphasizes feasibility and value, and standard business-case logic centers on comparing expected costs and benefits of proposed solutions. This is the most important inclusion because it directly supports the investment decision.
Option B is important for execution planning, but it is secondary to determining whether the investment makes sense. Option C is too absolute; feasibility studies should assess material risks, but not every possible scenario must be demonstrated. Option D supports governance, but it is not the core analytical content of a feasibility study.
References (Official ISACA):
* ISACA, An Appropriate Approach for Program and Project Management.
* ISACA Journal, Managing the Practical Risk Assessment.