The primary responsibility of quality control (QC) in software development is to detect and correct defects in the product through activities such as testing and verification. QC ensures that the software meets defined quality standards and functions as intended before deployment.

The highest priority for an IS auditor when reviewing disaster recovery planning (DRP) tests for an e-commerce company should be an application for financial management. This is because financial transactions, payments, and accounting are critical to the business's revenue and operations. Any downtime or failure in this area could have severe financial and legal consequences, making it the most critical application to ensure recovery procedures are in place and tested effectively.