Sulfuric Acid Is Prepared Commercially by the Following Series of Reactions

Sulfuric acid is prepared commercially by the following series of reactions:
A.Sulfur is burned in oxygen to produce sulfur dioxide.
B.Sulfur dioxide is further reacted with oxygen to form sulfur trioxide.
C.Sulfur trioxide is reacted with sulfuric acid to produce pyrosulfuric acid,H₂S₂O₇.
D.Pyrosulfuric acid is reacted with water to produce sulfuric acid.
Write a balanced chemical equation for each step in the commercial production of sulfuric acid.