When entering information for a sales order, which of the following data entry controls is designed to identify the entry of a nonexistent customer: a. Sequence check b. field check c. validity check d. redundancy check e. Completeness check When preparing the REA diagrams, one should ensure that it meets economic duality. Economic duality states that every entity (such as resources and events) should be linked to two stock flow one of which increments (increases) the entity and one that decrements (decrease b. every resource entity should be linked to two stock flow events, one of which increases the resource and one that decreases it. c. every agent entity that increases a resource must be linked to an agent entity the decreases a resource. d. every economic exchange event that increases a resource must be linked to an economic exchange event that decreases a resource