The resistances P,Q,R and S in the bridge shown are adjusted such that the deflection in the galvanometer G is zero when both the keys `K_(1)` and `K_(2)` are inserted. The galvanometer will show a momentary deflection if

Options

A. first `K_(2)` is inserted and then `K_(1)`
B. first `K_(1)` is inserted and then `K_(2)`
C. `K_(1)` and `K_(2)` are both inserted but an additional resistance is put in the arm BD
D. in all the above cases

Answer

A