Which of the following statements regarding process yield is true?

a. Process yield is the most appropriate way to assess performance in the service industry.
b. In computing process yield, output is measured as the percentage of units from a process that pass inspection.
c. Process yield of 100% is possible, irrespective of the nature of the process.
d. Process yields of various processes are added to compute overall process yield if several processes are required to manufacture a product.