Which statement is true of BGP communities?

Which statement is true of BGP communities?

A.
Communities are used to identify BGP routes based on the originating route’s attributes, whether it is an internal route, an external route, or unknown.

B.
Communities are added by route reflectors. A route reflector appends its own IP address and the autonomous system number separated by a colon in the community field each time a route traverses it.

C.
Communities are used to determine preference within a network; lower community values are more preferable than higher values.

D.
Communities are used as a tool for sorting and categorizing routes based on user-defined criteria.