Final answer:
SOAs are implemented most commonly with Web services, allowing functions to be distributed over the internet. Service-oriented architectures are about design principles for software, not specific network types like LANs or WANs.
Step-by-step explanation:
Service-oriented architectures (SOAs) refer to a set of design principles used for building software in the form of interoperable services. These services are loosely coupled functions that provide broad-ranging functionalities over a network which can be consumed by clients. Among the given options, SOAs are indeed most commonly implemented using A. Web services. Web services enable these functions to be available over the internet, thus allowing for greater flexibility and interoperability among different systems and platforms.
Service-oriented architectures are not typically defined by their association with value-added networks (VANs), local area networks (LANs), or wide area networks (WANs), even though the functions they encapsulate can be accessed over these types of networks. Specifically, LANs and WANs are more about the infrastructure for network connectivity rather than the design of interoperable services, and VANs are typically used for a specific type of secure data exchange often in the context of electronic data interchange (EDI).