Correct Answer - A
Left loop :
`V_F +6 +4I_1 - 30 +2I_1 = V_F`
`I_4 = 4A`
Right loop :
`V_F +6+ 1I_2 - 15 + 2I_2 =V_F 30V`
or `I_2 =3A`
Net current through 6V battery is
`I = I_1 +I_2 = 4+3 = 7A`
The 6 V battery is getting charged. Both 15V and 30V batteries
produce current in 6V battery.