Which of the following is a correct statement regarding the nature and timing of communications between an accounting firm performing an initial audit of an issuer and the issuer's audit committee?
a. prior to accepting the engagement, the firm must orally affirm its independence to the audit committee with all members present.
b. the firm must address all independence impairment issues on the date of the audit opinion.
c. communications related to independence may occur in any form prior to issuance of the financial statements.
d. prior to accepting the engagement, the firm should describe in writing all relationships that, as of the date of the communication, may reasonably be thought to bear on independence.