Final answer:
When an enterprise installs a new accounting system, the inherent risk increases because of potential issues with system implementation and the increased complexity. Option (b) Increase in inherent risk is the correct answer to how the audit risk model is affected for the current year. The audit risk overall may increase but inherently risk increase is more specific and the main effect relevant to the question.
the correct option is (b) Increase in inherent risk.
Step-by-step explanation:
The question revolves around how the installation of a new enterprise resource planning system affects the audit risk model in the current year. This new system introduces changes to how financial transactions are processed and reported, which would likely increase the inherent risk due to the potential for errors or fraud that could occur because of the newness and complexity of the system.
Detection risk generally pertains to the auditor's ability to detect material misstatements, which is not directly affected by the change in the accounting system. Control risk may be affected, but typically, a new system's implementation would not immediately decrease control risk as it would still be unproven and subject to potential errors or bugs. Overall, audit risk can increase but it is not the best description of the 'main affect' as requested in the question since it is a result of changes in inherent, control, and detection risks.
Therefore, the correct option in the final answer is (b) Increase in inherent risk.