Final answer:
An unexplained decrease in the scrap account is not a red flag in a fraudulent shipment scheme; it could indicate efficiency improvements, unlike the other options, which are typical fraud indicators.
Step-by-step explanation:
The question refers to indicators of potential fraudulent shipment schemes within a business context. An unexplained decrease in the scrap account is not typically a red flag of fraudulent shipments. Fraudulent schemes often include an increase in bad debt expense (as bad receivables are written off), unusually high levels of reorders for inventory items (indicating possible theft or unauthorized shipments), and shipments with missing sales documents (suggesting a lack of proper authorization or recording).
However, an unexplained decrease in the scrap account might indicate efficiency improvements or a reduction in waste, which are generally positive outcomes for a company. It is not an immediate indicator of fraud like the others.