For a large-scale network with 15,000 wireless terminals, a three-layer hierarchical network architecture is the most appropriate and recommended solution. This model consists of a core layer, an aggregation layer, and an access layer. It provides the highest levels of scalability, performance, resilience, and manageability required for such a large user base. The aggregation layer is critical for summarizing traffic, enforcing policies, and distributing the load before it reaches the network core. A native WAC, integrated into a core or aggregation switch, simplifies the network architecture and centralizes management, which is highly beneficial in large deployments.

B. Combining aggregation and access layers is a design for medium-sized networks and would likely create performance bottlenecks and management complexity with 15,000 users.

C. This is a collapsed core design suitable only for very small networks. It is not scalable for the number of access points required to support 15,000 terminals.

D. A two-layer architecture (core and access) is suitable for medium-sized networks but lacks the scalability and policy enforcement capabilities of a dedicated aggregation layer for a large-scale deployment.

1. Huawei Enterprise Support Documentation: In the Huawei CloudCampus Solution Design Guide, the standard networking model for a large campus network (typically defined as supporting thousands of users) is the three-layer architecture of core, aggregation, and access switches. This design ensures high reliability and allows for future expansion. The guide also details the deployment of native WAC functionality on core or aggregation switches for centralized WLAN management. (Refer to: Huawei CloudCampus Solution Design Guide, Section: "Network Design > Campus Network Architecture Design > Large and Medium-Sized Campus Network Architecture").

2. University Courseware: Network design principles taught in advanced networking courses advocate for a hierarchical model for scalability. For instance, Stanford's CS144 (Introduction to Computer Networking) course materials explain that large enterprise networks are built hierarchically (Core, Distribution/Aggregation, Access) to manage complexity, provide scalability, and isolate failures. This principle directly applies to designing a network for 15,000 users. (Reference: General principles covered in curricula like Stanford CS144 or MIT 6.829).

3. Official Vendor Documentation: Huawei's documentation for its CloudEngine series switches, which often serve as core and aggregation devices with native WAC capabilities, consistently presents the three-layer architecture as the best practice for large campus networks. This ensures that performance, forwarding capacity, and port density requirements are met efficiently. (Refer to: CloudEngine S12700E Series Switches Documentation, Section: "Typical Applications > Large-Scale Campus Network").