Which of the following is a good example of an IT application control over the occurrence of revenue transactions?

a. Physical access to IT systems is limited only to specific personnel who work in the revenue cycle.

b. The software application compares information on a sales invoice with information from the bill of lading to ensure that sales invoices are only prepared for actual shipments. Any exceptions are not processed and are set aside for manual follow-up.

c. The software changes to the revenue program must be tested and authorized before they may be used with live data.

d. Strong segregation of duties exists between IT operations and IT program development.