A project manager is performing quality assurance for a project whose quality standards are very stringent. In order to meet and exceed the quality requirements, the project manager uses a set of technical guidelines, which were applied during the design phase of the project to optimize quality.

What tool or technique is the project manager using in this scenario?

Question $3$ options:

Design for X $($DfX$)$ where the X in DfX represents the quality aspect of the product

Design of experiments $($DOE$)$ as a quality improvement methodology

The Manage Quality process to ensure compliance with project quality requirements