The correct option is
B Cl−CH2−CH3|C|CH3−CH2−CH2−I CH3 CH3
Cl−CH2−|C|−CH2−CH2−Cl+I−DMF−−−→Cl−CH2−|C|−CH2−CH2−I
CH3 CH3
DMF is dimethylformamide. It ia an organic compound with formula of (CH3)2NCH. DMF is a polar aprotic solvent with a high boiling point and facilitates reactions that follow polar mechanisms, such as SN2 .