Final answer:
The written communication that includes the auditor's commitment to provide reasonable assurance for the detection of fraud is found in the engagement letter.
Step-by-step explanation:
The written communication in which the auditor will provide reasonable assurance for the detection of fraud is found in the engagement letter. An engagement letter is a formal document that outlines the scope of work, responsibilities, and the terms of the audit between the auditor and the client. It typically specifies the objectives of the engagement, the scope of the auditor's work, and the auditor's responsibilities with regard to fraud detection.
While a representation letter is a document prepared by company management and provided to the auditor asserting the truthfulness and accuracy of the financial statements, a responsibility letter or client letter is not a standard term in the context of auditing.