Sergio identifies a conflict of interest in connection with his tax client, Company C. Which is he required to do under Circular No. 230?

a) Email copies of written consents to the SEC's Office of the Chief Accountant.

b) Email copies of written consents to all interested parties.

c) Obtain written statements from the affected parties that they will not sue him.

d) Obtain written, informed consent to perform the service from each affected client.