As shown in the figure, two two identical capacitors of `C_1" and "C_2` are connected with a battery. `C_1` is filled with air and `C_2` is filled with an insulator of dielectric constant `in_r` then
A. `Q_1 gt Q_2`
B. `Q_1 lt Q_2`
C. `Q_1 = Q_2`
D. none