Which of the following fraudulent activities most likely could be perpetrated due to the lack of effective internal controls in the revenue cycle? a. merchandise received is not promptly reconciled to the outstanding purchase order file. b. obsolete items included in inventory balances are rarely reduced to the lower of cost or market value. c. the write-off of receivables by personnel who receive cash permits the misappropriation of cash. d. fictitious transactions are recorded that cause an understatement of revenue and overstatement of receivables.