ABC, CPA, is the auditor in charge of the XYZ, Inc. engagement for the year ended December 31, 2002. The following replies have been received in response to six accounts receivable confirmation requests: Balance per Confirmation Balance per Customer Explanation (A) $12,000 $4,000 Paid 1/9/03 (B) 46,882 12,882 Returned goods for credit on 12/29/02 (C) 67,921 10,000 Sales invoice #S3003, dated 1/4/03 in the amount of $57,921, for goods received 1/3/03 (D) 16,364 16,364 No exception (E) 98,500 unknown Unable to confirm. Customer accounts for transactions only. No record of balances maintained by customer. (F) 64,000 16,000 Remainder in dispute REQUIRED: What auditing procedures should ABC apply to satisfy herself regarding the above confirmation replies