\text { 6. In the reaction equation } \mathrm{Co}(\mathrm{s})+2 \mathrm{HCl}_{\text {(aq) }} \rightarrow \mathrm{CoCl}_{2(\mathrm{aq})}+\mathrm{H}_{2(\mathrm{~g})} a. Chloride is oxidized b. Hydrogen is reduced C. Hydrogen is oxidized d. Cobalt is reduced