Choice "D" is correct. Blank forms may result in lower response rates because a greater effort is required for response.
Choice "b" is incorrect. Use of the blank form does not necessarily imply that subsequent cash receipts will need to be verified. This is an alternative procedure that might be used to follow up on nonresponses.
Choice "a" is incorrect. The decision regarding whether or not to use statistical sampling is independent of the decision regarding what form of accounts receivable confirmation to use.
Choice "c" is incorrect. Blank forms provide a greater degree of assurance, since the recipient cannot simply sign off without checking the balance. A greater degree of assurance results in a lower assessed level of detection risk.