Final answer:
The principle that is not a basic part of an accounting information system among the listed options is 'periodicity,' which is an accounting principle relating to time periods, not a characteristic of the system.
Step-by-step explanation:
The question pertains to the basic principles of an accounting information system. Of the options provided, periodicity is not considered a basic principle. The basic principles typically include cost effectiveness, meaning the system should provide value for the money spent on it; flexibility, indicating that the system should be able to adapt to changes in the business environment; and useful output, signifying that the system should generate information that is relevant and helpful for decision-making. Periodicity is actually an accounting principle that relates to the time periods over which business operations are reported, not directly to the characteristics of an accounting information system itself.
The basic principles of an accounting information system include cost effectiveness, periodicity, flexibility, and useful output. Therefore, the correct answer to this question is none of the above as all the options listed are actually principles of an accounting information system.