Which of the following statement about Document Set is wrong?

Question $15$Select one:

a$.$

Document Set is a content type in SharePoint by default.

b$.$

The files or documents in a Document Set is actually saved inside a folder in the computer's file system.

c$.$

The Document Set can have a welcome page.

d$.$

Document Set is used to handle multiple pieces of contents together as a unit and should never be used as a parent content type.