Which of the following circumstances would be least likely to impair the independence of a CPA firm?

a. The spouse of a member of the attest engagement team is employed in a key financial position with the attest client

b. A partner in the same office as the lead partner on the attest engagement is currently in an immaterial joint business venture with the attest client

c. A professional employee of the firm who does not provide any services to the attest client was formerly employed by the client, during the period under review

d. A partner who provides non-attest services to the attest client owns 100 shares of the clients 20,000,000 outstanding shares