Which of the following is not a way by which the Sarbanes–Oxley Act attempts to ensure auditor independence from an audit client?

  a. The auditing firm must be appointed by the client’s audit committee.
  b. Audit fees must be approved by the Public Company Accounting Oversight Board.
  c. The audit committee must be composed of members of the client’s board of directors who are independent of the management.
  d. The external auditor cannot also perform financial information system design and implementation work.