An architectural style defines as a family

问题：

An architectural style defines as a family of such systems in terms of a（71） of structural organization. More specifically, an architectural style defines a vocabulary of（72） and connector types, and a set of（73）on how they can be combined. For many styles there may also exist one or more（74）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（75）architectures are programs written in the Unix shell.

A．event-based

B．object-oriented

C．pipe-and-filter

D．layered