Which process is designed to proactively act before a problem occurs?

Common cause variation refers to the inherent, stable, and predictable variations in processes that occur under normal operating conditions. Addressing these variations typically involves understanding and improving the overall system rather than proactively preventing issues. Therefore, this choice does not specifically target proactive measures before problems occur.

Quality control is primarily concerned with identifying and correcting defects in products or services after they have been produced. This reactive approach focuses on inspection and testing to ensure that outputs meet the required standards, rather than taking preventative actions to stop issues before they manifest.

The Plan-Do-Check-Act (PDCA) cycle is a continuous improvement process that involves planning, implementing, checking, and acting on changes to improve outcomes. While it encompasses proactive elements, it is not exclusively designed for prevention; rather, it addresses both proactive and reactive adjustments based on performance evaluations.