You work in internal audit and have recently completed a fraud risk review. You have identified an opportunity for the Accounts Receivable clerk to divert invoices and late notices so customers don't receive notice of payments not being recorded thereby concealing theft of cheques. Which of the following controls could mitigate this risk? 

Requiring manager approval for cash and cheque disbursements 

Requiring receipts to be submitted 

Implementing segregation of duties so that employees executing sales do not also perform inventory counts and write-offs 

Implementing segregation of duties so that employees receiving payments do not also send invoices to customers