Alsap Corporation's April 1999, $35 million initial public offering included Singer & Revine's unqualified opinion on Alsap's December 31, 1998 audited financial statements. Owing to material misstatements related to inventory and receivables, securities purchasers sued Singer & Revine, who likely can avoid liability if:

a. Singer & Revine can demonstrate due diligence.

b. Singer & Revine's engagement letter called for mediation and arbitration.

c. Alsap management caused the misstatements.

d. Some of the purchasers did not rely on the audited financial statements.

Choose the correct answer.