Lean Six Sigma is the methodology that directly combines defect reduction, variation reduction, cycle-time improvement, and waste elimination in a unified approach focused on customer satisfaction. Six Sigma contributes statistical rigor, process capability improvement, and variation control, while Lean contributes speed, flow, waste reduction, and value-added focus. Together, they address both effectiveness and efficiency. This combined methodology is widely used to improve quality, lower cost, shorten lead time, and strengthen customer experience by aligning processes with what customers truly value. Total quality management is broader and more cultural, PDCA is a general improvement cycle, and Kaizen emphasizes continuous incremental improvement. While each of those supports quality improvement, Lean Six Sigma is the specific methodology that explicitly targets defects, variation, cycle time, and waste together. In CSSBB practice, this integrated approach is essential because customer dissatisfaction often results from a combination of poor quality, slow processes, inconsistency, and non-value-added activity. Therefore, the correct answer is Lean Six Sigma, since it best matches the full set of improvement objectives described in the question.

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