Consider the following redox reaction: 2 Cr³⁺(aq) + 3 Cu(s) → 2 Cr(s) + 3 Cu²⁺(aq). The reaction:
A. Must be carried out in an electrolytic cell.
B. Can be carried out in a galvanic cell.
C. Has a positive emf value.
D. Is spontaneous at standard states and 25°C.