Identify the reactions in which dichromatc acts as an oxidising reagents :
A. `Cr_(2)O_(7)^(2-)+6Fe^(2+)+14H^(+) to 6Fe^(3+)+7H_(2)O`
B. `Cr_(2)O_(7)^(2-)+2OH^(-) to 2CrO_(4)^(2-)+H_(2)O`
C. `Cr_(2)O_(7)^(2-)+6I^(-)+14H^(-) to 2Cr^(3+)+3I_(2)+7H_(2)O`
D. `Na_(2)Cr_(2)O_(7)+2KCl to K_(2)Cr_(2)O_(7)+2NaCl`