Two condensers `C_1 and C_2` in a circuit are joined as shown in figure. The potential of point A is `V_1` and that of B is `V_2` . The potential of point `D` will be
Options:
(a) `1/2(V_1+ V_2)`
(b) `(C_2V_1+C_1V_2)/(C_1+C_2)`
(c) `(C_1V_1+C_2V_2)/(C_1+C_2)`
(d) `(C_2V_1-C_1V_2)/(C_1+C_2)`