Which Statement Is Correct When Packing Retraction Cord

Which statement is correct when packing retraction cord?

A) It is important to place the retraction cord into the sulcus without damaging the surrounding gingival tissues.
B) The placement and removal of gingival retraction cord are expanded functions and may be performed by a dental assistant trained in expanded functions.
C) Generally, the operator removes the cord while the assistant prepares the impression material.
D) All of the above are correct.