Explanation: Traditional network architectures typically rely on distributed control, where each device (router, switch, etc.) operates independently and must be manually configured. This means that changes, troubleshooting, and maintenance require hands‑on work on each individual device (Option A) and that the control plane—responsible for routing decisions—is embedded within each device (Option C). Controller‑based networking (a key aspect of software‑defined networking, or SDN) changes this paradigm. In SDN, a centralized controller manages the network and communicates with devices via standardized protocols. This centralization (Option B) simplifies management by allowing policies and configurations to be applied uniformly across the network. Moreover, SDN architectures deliberately separate the control plane from the data plane (Option D). The controller makes decisions and pushes instructions to the devices, which focus solely on forwarding packets. Option E is incorrect because traditional networks generally lack native support for programmatic, API‑driven configuration. While automation can be added later through scripting or management systems, controller‑based networks are designed from the ground up with APIs (especially northbound APIs) that enable seamless integration with automation and orchestration tools. Together, these differences highlight why many organizations are shifting toward controller‑based networking: the centralized control and separation of planes allow for greater agility, scalability, and automation in managing modern networks.