Final answer:
Creating a hosted control in USD allows for varying fields based on the control type, and setting of a default action is possible, while there are more than five control types and the owner can be changed.
Step-by-step explanation:
When creating a hosted control in the Unified Service Desk (USD), it is true that the fields that display on a form can vary depending on the type of hosted control being used.
This aspect allows for USD to be highly customizable based on the specific needs of the control. It is also true that you can set a default action for the control, which specifies the standard behavior the control will follow upon being invoked.
As for the number of hosted control types available, there are more than five, making option C incorrect.
Regarding the owner for the hosted control, it can indeed be changed after creation, which means option D is incorrect as well.