Chapter 5, Problem 47E

What are the oxidizing and reducing agents in the following redox reactions?
a. ${\text{5SO}}_{\text{:-3}}^{2-}{\text{+2MnO}}_4{\text{+6H}}^{\text{+}}\to {\text{5SO}}_{\text{4}}^2{\text{ +2Mn}}^{\text{2+}}{\text{+3H}}_{\text{2}}\text{O}$
b. ${\text{2NO}}_{\text{2}}\left(\text{g}\right){\text{+7H}}_{\text{2}}\left(\text{g}\right)\to {\text{ 2NH}}_3\left(\text{g}\right){\text{+ 4H}}_{\text{2}}\text{O}\left(\text{g}\right)$
c. $\text{2}{\left[\text{Fe}{\left(\text{CN}\right)}_{\text{6}}\right]}^{\text{4-}}{\text{+H}}_{\text{2}}{\text{O}}_{\text{2}}{\text{+2H}}^{\text{+}}\to \text{ 2}{\left[\text{Fe}{\left(\text{CN}\right)}_6\right]}^{3-}{\text{+ 2H}}_{\text{2}}\text{O}$