73. The AICPA Code of Professional Conduct states that a CPA shall not disclose any confidential information in the course of a professional engagement, except with the consent of the client. This rule should be understood to preclude a CPA from responding to an inquiry that is received from:

a. an investigative body of a state CPA society.

b. the Trial Board of the AICPA.

c. a CPA-shareholder of the taxpayer corporation.

d. an AICPA voluntary quality review body.

Explain your answer.