In the figure shown, `m_(a)=m_(b)=1kg` block-`A` is neutral while block-`B` carries charge `-1c`. Sizes of `A` and `B` are negligible. Block-`B` is released from rest at a distance `1.8m` from `A`. Initially spring is neither compressed nor stretched.
The amplitude of oscillation of the combined mass
A. `(2)/(3)m`
B. `(sqrt(124))/(3)m`
C. `(sqrt(72))/(9)m`
D. `(sqrt(106))/(9)m`