How can an Administrator accomplish this using Flow?

The system needs to automatically mention the record owner in the record feed whenever an Opportunity record is Closed-Won.

How can an Administrator accomplish this using Flow?
A . By cresting two flow directives, one for the record and another one for the feed item.
B . By using the Assignment Element and setting the value to the record owner.
C . By creating a temporary shadow record with system account as the owner and copying the lead item to original record.
D . By entering @[reference] in the input Message parameter, where reference is the ID for the record owner.

Answer: D