Which of the following statements regarding "quality" is true?

a. Improving quality increases sales through higher customer satisfaction and demand, reduces costs, and increases the long-term profitability of companies.

b. Over the past 20 years or so, the demand by customers for quality products and services at an affordable price has drastically changed the way companies do business.

c. Companies have focused on improving the quality of the products or the services they sell through a variety of initiatives, such as total quality management (TQM), market-driven quality, and strategic quality management.

d. All of these are true