Which of the following is characteristic of a system? 

A)  A system functions in a regular and predictable manner. 
B)  A system consists solely of inputs and outputs. 
C)  A system cannot be accurately modeled. 
D)  A system is highly random in its function.

A system is characterized by its regular and predictable functioning, where inputs are transformed into outputs according to specific rules or processes. It is not solely made up of inputs and outputs, as there may be internal components and processes that mediate the transformation of inputs to outputs. A system can be accurately modeled, although the complexity of the system may affect the accuracy of the model. A system is not inherently random in its function, although randomness or variability may be present in some types of systems.