Le Chatelier's Principle says that when something disrupts the equilibrium, the system adjusts to minimize the effect of that disturbance. If 0.1 M HCl solution is added, this dissociates into H+ and Cl- ions, so there will be more Cl- ions in the system. This causes the reaction to go in the reverse direction (equilibrium shifts to the left) to reduce the amount of Cl-.
Since this also consumes Ag+ ions, the concentration of Ag+ (aq) will decrease.
The answer is the second choice.
