To segment Azure resources for different departments and allow each department's administrator to manage their own resources, two effective techniques are: creating multiple subscriptions (Option A) and using multiple resource groups (Option D). A subscription is a container for Azure resources and provides a boundary for permissions and billing. Each department can be assigned a separate subscription, so their resources are managed independently. Resource groups, on the other hand, allow for logical grouping of resources for easier management within a subscription. Using both methods ensures proper segmentation and management of resources by department administrators.