Software-defined networking architecture is used for cost-effective, adaptable, and easily manageable applications.

A (SD-WAN):SDN principles are widely adopted in wide area networks for dynamic path selection, centralized control, and policy enforcement.

B (Mobile networks):5G and modern mobile networks leverage SDN/NFV architectures to virtualize core services and optimize resource utilization.

Other options explained:

C: Metro networks adopt SDN, but WAN and mobile are more common mainstream use cases.

D/E: Application and control network are not direct SDN network types.