Final answer:
The SALES_INVOICES are triggered by the ORDER_ENTRY entity in the E-R diagram for OE/S.
Step-by-step explanation:
The SALES_INVOICES are triggered by the ORDER_ENTRY. In the E-R (Entity-Relationship) diagram for OE/S (Order Entry/Shipping), the ORDER_ENTRY entity is responsible for creating sales invoices when an order is made. When a customer places an order, the sales invoice is generated by the ORDER_ENTRY process.