How do you ensure .Product always contains the most current data from the data page?

The page .Product contains data retrieved from an external system of record using a data page.

How do you ensure .Product always contains the most current data from the data page?
A . Select Refer to a data page on .Product.
B . Select Copy data from a data page on .Product.
C . Configure .Product to refer to a keyed data page.
D . Define a reference property that refers to the data page.

Answer: D