Match Column-$I$ and Column-$II$ with the correct relation:

Column-$I$	Column-$II$
$(i).$ Magnesium pyrophosphate	$(a).$ $I_2O_5$
$(ii).$ Barium sulphate	$(b).$ $AgX$
$(iii).$ Iodide pentoxide	$(c).$ $Mg_2P_2O_7$
$(iv).$ Silver halide	$(d).$ $BaSO_4$

(C) The correct matches are as follows:
$(i)$ Magnesium pyrophosphate is $Mg_2P_2O_7$ (used in phosphorus estimation).
$(ii)$ Barium sulphate is $BaSO_4$ (used in sulfur estimation).
$(iii)$ Iodide pentoxide is $I_2O_5$ (used in oxygen estimation).
$(iv)$ Silver halide is $AgX$ (used in halogen estimation).
Therefore,the correct sequence is $(i-c, ii-d, iii-a, iv-b)$.