Calcium Oxide Is Added to Molten Iron in the Production

Calcium oxide is added to molten iron in the production of carbon steel in order to

A) convert silicon and phosphorus oxides to slag which can be decanted from the molten steel.
B) serve as a scrubber to remove sulfur dioxide from the gases leaving the furnace.
C) remove any traces of acid which could weaken the steel.
D) add a small amount of oxygen to the steel to prevent corrosion and increase its strength.
E) create gangue.