When Casting Water-Filled Impressions a Retaining Wall Should Be Placed

When casting water-filled impressions a retaining wall should be placed around the impression and _______________.

A) Dental stone should be sifted directly into the impression and followed by normally prepared dental stone
B) Snow wax should be sprayed into the impression and followed by normally prepared dental stone
C) Dental stone should be prepared normally and the impression filled to at least 4 inches thick
D) The water should be vacuumed from the impression and dental stone prepared normally to fill the impression