Kate Is an Underwriter Who Acted as a Third Party

Kate is an underwriter who acted as a third party conducting a sale of securities between Fox Co. and an investor. Subsequent to the sale it is discovered that the disclosures made by Fox Co. were fraudulent. The investor has sued both Fox Co. and Kate. What is Kate's best defense to avoid liability?

A) proving that she actually did not profit from the transaction
B) proving that the fraud was so sophisticated that even if she had investigated the preregistration and registration documentation, she probably wouldn't have discovered the fraud anyway
C) proving that the issuing company had a long history of truthful disclosures and had never been suspected or investigated for fraud, so she was able to rely on their representations
D) proving that she exercised due diligence in examining the preregistration and registration documentation and did not discover the fraud