The correct option is C 10.3 rad/s
Initial angular momentum of bullet + initial angular momentum of cylinder
= Final angular momentum of (bullet + cylinder) system
⇒mvr+I1ω=(I1+I2)ω′
⇒mvr+I1ω=(12Mr2+mr2)ω′
⇒0.5×5×0.2+0.12=(122(0.2)2+(0.5)(0.2)2)ω′
∴ω′=10.3rad/sec.