单项选择题
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．
The best-known examples of （） architectures are programs written in the Unix shell．
A．event-based
B．object-oriented
C．pipe-and-filter
D．layered