What is the reducing agent in the reaction below?

\[2{\text{MnO}}_4^ - ({\text{aq)}} + {\text{B}}{{\text{r}}^ - }({\text{aq)}} + {{\text{H}}_2}{\text{O(l)}} \to {\text{2Mn}}{{\text{O}}_2}{\text{(s)}} + {\text{BrO}}_3^ - ({\text{aq)}} + 2{\text{O}}{{\text{H}}^ - }({\text{aq)}}\]

A.     \({\text{B}}{{\text{r}}^ - }\)

B.     \({\text{BrO}}_3^ - \)

C.     \({\text{MnO}}_4^ - \)

D.     \({\text{Mn}}{{\text{O}}_{\text{2}}}\)

A