2AgCl(s)+H2(g)(1bar)⟶2HCl(aq)+2Ag(s)
The cell with this cell reaction can be represented as : (anode)Pt(s)∣H2(g)(1Bar)∣1MHCl(aq), ∥ (cathode) ∥Ag+(aq)∥Ag(s)
silver is undergoing reduction (Ag+⟶Ag)
in this reaction, hence it will act as cathode in
the cell.
Option (a) has KCl which is not present in the cell, so it is incorrect. (c) has AgCl(s) and AgCl do not ionise, it is also incorrect. (d) at cathode Ag is being oxidised to Ag+ and at cathode oxidation does not take place hence it is also incorrect.
Remember LEO⟶ loss of electrons is oxidation.