Answer:
Option A
Explanation:
In the cell represented by
$Pb(s)|Pb^{2+}(1M)|| Ag^{+}(1M)|Ag(s)$ , the
reducing agent is Pb because it readily gets oxidised to Pb2+ and helps in the reduction of $Ag ^{+}$ to Ag(s).
$Pb(s)\rightarrow Pb^{2+}(1M)+2e^{-}$
$Ag^{+}+1e^{-}\rightarrow Ag(s)$