Choice "C" is correct. The AICPA's Statements on Quality Control Standards assert that professional development policies and procedures should be established by the firm in order to provide reasonable assurance that personnel will have the knowledge required to perform their work and progress within the firm.
Choice "d" is incorrect. The auditors' responsibility is to the public and is defined in the "AICPA Code of Professional Conduct," which includes a set of mandatory rules and which derives its authority from the bylaws of the AICPA.
Choice "b" is incorrect. Supervision and review are part of GAAS fieldwork standards.
Choice "a" is incorrect. Accounting and review services pertain to the unaudited financial statements of a nonpublic company.