Which two objects can be dragged to a Mapping?

Which two objects can be dragged to a Mapping? (Choose two.)

A.
Variables

B.
Datastores

C.
Knowledge Modules

D.
Reusable Mappings

Explanation:
Explanation/Reference:(https://docs.oracle.com/middleware/1212/odi/ODIDG/mappings.htm#ODIDG1560)