Which of the following statements is correct about the given reaction?
$4Fe_{(s)} + 3O_{2_{(g)}} \to 2Fe_{2}O_{3_{(s)}}$

• A
  Total mass of iron and oxygen used in reaction $=$ total mass of ferric oxide in product; therefore,it follows law of conservation of mass.
• B
  Total mass of reactants used in the reaction $=$ total mass of product; therefore,law of multiple proportions is followed.
• C
  Amount of $Fe_{2}O_{3}$ can be increased by taking any one of the reactants (iron or oxygen) in excess.
• D
  Amount of $Fe_{2}O_{3}$ produced will decrease if the amount of any one of the reactants (iron or oxygen) is taken in excess.