Consider a galvanic cell based on the following half reactions:

$$\textrm{Co}^{2+}(aq) + 2e^- \rightarrow \textrm{Co}(s) \qquad E°=-0.28 V$$

$$\textrm{Cr}^{3+}(aq) + 3e- \rightarrow \textrm{Cr}(s) \qquad E°=-0.73 V$$

Which of the following changes to the galvanic cell would lead to a decrease in the cell potential? Select **ALL** that apply.