Determine whether each of the following is a preventive or detective control, and whether it is automated or manual. Controls Preventive or Automated or Detective? Manual? At month end, sales invoices are match with shipping documents by the computer system and an exception report is generated and reviewed. Payments by cheque are received in the mail by the receptionist, who lists the cheques, and endorses them The computer system verifies that all payroll payments have a valid employee identification number. The accounts receivable master file is reconciled to the general ledger on a monthly basis by the A/R manager. Invoices paid are stamped "paid" by the accounts receivable clerk