1. Identify the oxidation states of the elements in the reactants and products.
- Mn in MnO_2: +4
- Mn in MnCl_2: +2
- Cl in HCl: -1
- Cl in Cl_2: 0
2. Determine which element increases in oxidation state (oxidizes).
- Mn changes from +4 to +2 (reduces).
- Cl changes from -1 to 0 (oxidizes).
3. The species that oxidizes is Cl (Chlorine).
Answer: c) Cl