An analytical procedure is designed to recover silver from an acidic aqueous mixture containing \(\text{AgNO}_3\text{(aq)}\), \(\text{Fe(NO}_3)_2\text{(aq)}\), and \(\text{HNO}_3\text{(aq)}\). The procedure consists of two sequential stages:

Stage 1: Excess solid copper powder, \(\text{Cu(s)}\), is added to the solution. The copper selectively reduces all \(\text{Ag}^+\text{(aq)}\) to solid silver, \(\text{Ag(s)}\), while \(\text{Fe}^{2+}\text{(aq)}\) and \(\text{H}^+\text{(aq)}\) do not react. The resulting mixture is filtered to remove all solids.

Stage 2: An excess of aqueous potassium hydroxide, \(\text{KOH(aq)}\), is added to the clear filtrate, resulting in the neutralization of \(\text{H}^+\text{(aq)}\) and the complete precipitation of \(\text{Cu(OH)}_2\text{(s)}\) and \(\text{Fe(OH)}_2\text{(s)}\).

Which of the following correctly identifies the reducing agent in Stage 1, an intermediate species in the overall sequence, and an ion that acts as a spectator ion throughout both stages?