During a feasibility study on outsourcing IT processing, what is the key reason for an IS auditor to review the vendor's business continuity plan?

In the context of outsourcing IT processing, the review of the vendor's business continuity plan is crucial for evaluating the adequacy of the service levels the vendor can provide. A robust business continuity plan ensures that the vendor has established processes and strategies to maintain operations and deliver services during unforeseen events, such as natural disasters, cyber-attacks, or system failures.

By examining the business continuity plan, the auditor can ascertain whether the vendor is capable of meeting agreed-upon service levels. This involves assessing the plan's effectiveness in protecting data and ensuring that critical services remain operational under various adverse conditions. Ultimately, this evaluation is fundamental in determining whether the vendor can deliver the necessary reliability and stability that the organization expects in its IT processing services.

In this scenario, while other factors such as financial stability and staff experience may be important considerations when selecting a vendor, the primary concern in understanding how well the vendor can maintain service continuity directly aligns with the adequacy of service levels, making this the most pertinent reason for the audit.