Answer
Groups A and B: $Ag^{+}(aq) + Cl^{−}(aq) → AgCl(s)$
Groups C and D: $Ag^{+}(aq) + Br^{−}(aq) → AgBr(s)$
Work Step by Step
For the reactions in case of Groups A & B, Silver and chloride ions react. For the reactions in case of Groups C & D, Silver and bromide ions react.
