Customer credit histories are not checked before approving orders. This is resulting in excessive late collections and uncollectible accounts. Select one: a. Establish customer files and file sales orders by customers. b. Prepare, at a minimum, a three-part sales order, sending one to Shipping and one to Billing. Billing should match its copy with a signed copy from Shipping before preparing a sales invoice. c. Require a written customer purchase order as confirmation of telephone orders. d. Customers' credit should be checked and no sales should be made to those that do not meet credit standards