Option D is the most appropriate choice for this scenario. Amazon EKS is a fully managed Kubernetes service that can handle complex data processing tasks with high concurrency. When scaling the service to handle high concurrency, consider the choice of Kubernetes node types, which determine the CPU and memory resources available to the containers. Additionally, the number of nodes in the cluster should be chosen based on the workload requirements to ensure sufficient resources for processing tasks. To handle high concurrency, you can leverage Kubernetes' horizontal pod autoscaling feature, which automatically adjusts the number of pods based on CPU utilization or custom metrics.