Which cycle is central to ISO management system standards?

• A. The Plan-Do-Check-Act cycle.
• B. The PDCA cycle.
• C. The plan do check act cycle (PDCA).
• D. The PDCA cycle for quality.

Answer: (C)

The core concept is the PDCA cycle, a continuous improvement loop used across ISO management system standards. The idea is simple and universal: plan what you will do, implement it, check the results, and act to improve based on what you learned. The best answer presents both the full name and the acronym—Plan-Do-Check-Act cycle (PDCA)—which mirrors how ISO describes this cycle in its standards. This phrasing aligns with ISO terminology and reinforces that the approach applies to management systems in general, not just a single domain. A version that uses only the four words is equivalent in meaning but lacks the explicit reference to the PDCA shorthand, and the option that adds “for quality” narrows the concept to quality alone, which isn’t the exclusive scope of ISO management systems.