Correct Answer: A. Admin partitions that use dedicated VLANs

Short Explanation with reference: Admin partitions are a feature of Citrix ADC that allow administrators to create multiple logical partitions on a single physical appliance. Each partition is independent and isolated from the others, and has its own configuration, resources, and management. This enables administrators to delegate administration tasks to different departments or customers, while maintaining security and operational consistency1. Admin partitions can use dedicated VLANs to isolate the network traffic of each partition from the others2. A SNIP in each partition, and bind a VLAN for the department (option B) is also a valid way to isolate network traffic, but it does not provide configuration and management isolation. Policy-based routes for each department in the nsroot partition (option C) and dedicated routes in the admin partitions for each department (option D) are not relevant for isolating department-level administration, as they are used for routing traffic based on policies or routes3. Therefore, the correct answer is A. Admin partitions that use dedicated VLANs.