Donalds & Company, CPAs, audited the financial statements included in the annual report submitted by Markum Securities Inc. to the Securities and Exchange Commission. The audit was improper in several respects. Markum is now insolvent and unable to satisfy the claims of its customers. Customers have instituted legal action against Donalds based on Section 10(b) and Rule 10(b)- 5 of the Securities Exchange Act of 1934. Which of the following is likely to be Donalds’ best defense?

a. The firm did not intentionally certify the false financial statements.

b. Section 10(b) does not apply to the case.

c. The firm was not in privity of contract with the creditors.

d. The engagement letter specifically disclaimed any liability to any party that resulted from Markum’s fraudulent conduct.