Which of the following types of documentary evidence should the auditor consider to be the most reliable?

(1)A sales invoice issued by the client and supported by a delivery receipt from an outside trucker.

(2)Confirmation of an account payable balance mailed by and returned directly to the auditor.

(3)A check, issued by the company and bearing the payee's endorsement, that is included with the bank statements mailed directly to the auditor.

(4)An audit schedule prepared by the client's controller and reviewed by the client's treasurer.