Which of the following reactions are redox…

Which of the following reactions are redox…

Which of the following reactions are redox reactions? For those reactions that are redox reactions, identify the substance being oxidized and the substance being reduced.
a. Zn(s) + CoCl2(aq) ------> ZnCl2(aq) + Co(s)
b. HI(aq) + NaOH(aq) -------> H2O(I) + NaI(aq)
c. AgNO3(aq) + NaCI(aq) --------> AgCI(s) + NaNO3(aq)
d. 2 K(s) +Br2(I) --------> 2 KBr(s) 
Additional Requirements 
Level of Detail: Only answer needed