Hello,
Need assistance how to make choice in the custom field and come out with the list needed.
Example in the screenshot.

Example scenario:
Custom field = Region
Content in Region = Central, Northern
Content in Central = Station A, Station B
Content in Northern = Station C, Station D
When choose Region Central, custom field will list content in Central.
When Choose Region Northern , custom field will list content in Central.
What is the right Custom field to be used and any rules need to be apply?
Thanks.