20. Which of the following best describes the utility of the "roof" in the quality function deployment (QFD) matrix? A. The roof relates the customer attributes (CA) to the engineering characteristics (EC). B. The roof compares engineering characteristics (EC), which enables the study of any trade-offs among the EC. C. The roof provides the relative importance of the customer attributes (CA). D. The roof provides a competitive evaluation of the engineering characteristics (EC).