Consider the following reduction potentials:
Cd2+(aq) + 2e- Cd(s); E° = -0.40 V
Pb2+(aq) + 2e- Pb(s); E° = -0.13 V
Cu2+(aq) + 2e- Cu(s); E° = 0.34 V
Br2(l) + 2e- 2Br-(aq); E° = 1.07 V
Under standard-state conditions, which of the following reactions is spontaneous?