Final answer:
The tickler file of open purchase orders and receiving reports is the control that ensures input completeness by verifying that all expected purchase orders have been received and processed.
Step-by-step explanation:
The control most likely to address the goal of input completeness is d. tickler file of open purchase orders and receiving reports. This control is designed to ensure that all expected inputs, particularly in a procurement system, have been received and processed. Input completeness is about making sure that no expected pieces of data are missing from the system.
By maintaining a tickler file, the organization can monitor and verify that all purchase orders have corresponding receiving reports and that the system is not missing crucial pieces of information.