Final answer:
An effective business control system should be suitable for the task, understandable to its users, and provide timely information for decision-making.
Step-by-step explanation:
The three primary characteristics of an effective control system in a business are Suitable, Understandable, and Timely. These characteristics ensure that the control system is appropriate for the tasks at hand, can be easily comprehended by those who use it, and provides the necessary information or feedback promptly to allow for swift action. This contrasts with rigid systems, which may be too inflexible to adapt to change, or purely reactionary systems, which may not prevent issues before they occur.