Correct Answer - C
`U_(i)=(KQ_(1)Q_(3))/(0.8)+(KQ_(2)Q_(3))/(I)+(KQ_(1)Q_(2))/(0.6)`
`U_(f)=(KQ_(1)Q_(3))/(0.8)+(KQ_(2)Q_(3))/(0.2)+(KQ_(1)Q_(2))/(0.6)`
` /_U=U_(f)-U_(i)=(KQ_(2)Q_(3))/(I)-(KQ_(2)Q_(3))/(0.2)`
`=KQ_(2)Q_(3)(1-(1)/(0.2))`
`|U|=4KQ_(2)Q_(3)`