What Usually Initiates Data Input into a System

Multiple Choice

What usually initiates data input into a system?

A) The transaction system automatically checks each hour to see if any new data is available for input and processing.
B) The performance of some business activity generally serves as the trigger for data input.
C) A general ledger program is queried to produce a trial balance at the end of an accounting period.
D) Data is only input when a source document is submitted to the accounting department.