What is the principal methodology used to ensure that products have the desired quality?Quality assuranceQuality management systemSix SigmaTotal Quality Management

The principal methodology used to ensure that products have the desired quality can vary depending on the specific industry or company. However, here are brief explanations of the four methodologies you mentioned:

1. Quality Assurance: This is a way of preventing mistakes or defects in manufactured products and avoiding problems when delivering solutions or services to customers. It involves systematic activities implemented in a quality system so that quality requirements for a product or service will be fulfilled.

2. Quality Management System (QMS): A QMS is a collection of business processes focused on consistently meeting customer requirements and enhancing their satisfaction. It is aligned with an organization's purpose and strategic direction. It is expressed as the organizational goals and aspirations, policies, processes, documented information and resources needed to implement and maintain it.

3. Six Sigma: This is a set of techniques and tools for process improvement. It seeks to improve the quality of the output of a process by identifying and removing the causes of defects and minimizing variability in manufacturing and business processes.

4. Total Quality Management (TQM): TQM is a management approach to long-term success through customer satisfaction. It involves all members of an organization participating in improving processes, products, services, and the culture in which they work.

Each of these methodologies can be effective in ensuring product quality, and many organizations use a combination of these approaches. The choice of which to use can depend on the specific quality goals of the organization, the nature of the product, and other factors.