PD across the circuit will be
V=i(R1R2R1+R2)=1.2×6×46+4
⇒V=2.88 V
So, current through 6 Ω resistance will be
i1=VR=2.886=0.48 A
Alternative solution:
From current division law,
i1=i(R2R1+R2)
⇒i1=1.2(46+4)=1.2(410)
∴i1=0.48 A
Hence, option (b) is correct.