单选题
An architectural style defines as a family of such systems in terms of a ______ of structural organization. More specifically, an architectural style defines a vocabulary of ______ and connector types, and a set of ______ on how they can be combined. For many styles there may also exist one or more ______ that specify how to determine a system's overall properties from the properties of its parts. Many of architectural styles have been developed over the years. The best-known examples of ______ architectures are programs written in the Unix shell.
单选题
A. pattern B. data flow C. business process D. position level