Every Night, at Midnight, a System Automatically Raises Invoices for Customers

Multiple Choice

Every night, at midnight, a system automatically raises invoices for customers that have placed orders that day. The invoice is sent electronically by email to customers. What is the event that triggers the production of invoices?

A) Midnight on the system clock.
B) The receipt of an order from a customer.
C) The email system.
D) The batch invoice production job.