- Data streams
- Roll-up properties
The correct answer is: Roll-up properties
A roll-up property contains data from two or more source properties. It can include source data from ordinary properties and subproperties, but not other roll-up properties.
Roll-up properties provide a broad view of your business across products, brands, or regions by combining data from multiple source properties into a single roll-up property. For example, if you have separate properties for multiple brands that your company owns, you can roll those up to a single property that provides an aggregate look at how those brands perform.
Read more here: https://support.google.com/analytics/answer/11526039