Write the concentration equilibrium constant expression for this reaction:
Cu₂(aq) + 2Ag(s) → Cu(s) + 2Ag(aq)

a. [Cu][Ag]₂ / [Cu2][Ag]₂
b. [Cu] / [Ag]₂
c. [Cu][Ag]₂ / [Cu₂]
d. [Cu] / [Ag]₂[Cu₂]