The best answer is option A, which outlines the core Kanban practices for Scrum:
* Visualizing Flow: Helps the team see the state of work items at a glance.
* Limiting Work in Progress (WIP): Prevents overloading the team and promotes focus on completing work.
* Actively Managing the WIP: Ensures the team continuously monitors and manages the amount of work in progress.
* Inspecting and Adapting the Workflow: Regularly reviewing and adjusting the workflow to improve efficiency and effectiveness

A Kanban board is primarily used for visualizing the Workflow and managing WIP Limits. This visualization helps Scrum Teams make the flow of work transparent, track progress, and manage bottlenecks effectively.
Limiting WIP ensures a pull-based flow, where new tasks are only started when there is available capacity, preventing overburdening the team. References: The Kanban Guide for Scrum Teams.