Which one of the following includes four stages called Plan, Do, Check and Act?

The Deming Cycle (also called the PDCA cycle) was developed by W. Edwards Deming and consists of exactly four stages: Plan (identify the improvement), Do (implement it), Check (measure results), and Act (embed or adjust). It underpins ITIL's continual service improvement philosophy and is the source of the four-stage model described in the question.

The continual service improvement approach in ITIL uses a seven-step model, not a four-stage Plan-Do-Check-Act cycle.

The seven-step improvement process describes how to collect, process, analyze, and present data across seven distinct steps, not four PDCA stages.

The service lifecycle is a five-stage framework (strategy, design, transition, operation, CSI) and does not map to Plan, Do, Check, Act.