Correct Answer: B
Explanation:
Alkyl halides contain a halogen (X = F, Cl, Br or I) covalently bonded to a carbon atom. Due to the electronegativity differences between carbon and the halide, the C-X bond is polar with a partial positive charge (d +) on the carbon atom and a partial negative charge (d -) on the halogen. Halogens are good leaving groups and can be replaced by an incoming nucleophile as in the general reaction shown here.
Nu:- + R--X à R--Nu + X-