Which of the following statements about quality costs is true? a. Even in theory, external failure costs can never be reduced to zero. b. The less a company spends on prevention costs, the less they will have to spend on internal failure costs in the future. c. If a company produces and sells a defective product, external failure costs are likely to exceed all the other types of quality costs. d. A low level of internal failure costs usually indicates that more attention needs to be paid to prevention and appraisal costs