19. After an auditor has issued an audit report, there is no obligation to perform further TOC and TOB with respect to the audited financial statements covered by the audit report. However, the auditor should take certain steps to address: (Hint: Think of SDFs) a. any material factual event that has occurred after the audit report date and before the audit report issue date. b. any material factual event that has occurred after the audit report issue date, and the event relates to condition existed at the balance sheet date. completion of field work date relates to condition existed at the audit report date. c. any material factual event that has occurred after the balance sheet date and before the d. any material factual event that has occurred after the audit report date, and the event