For nucleophilic substitution bimolecure SN^2 reaction give the correct order of reactivity.

For nucleophilic substitution bimolecure SN2 reaction give the correct order of reactivity. (A) 20 halide < 30 halide < 10 halide (B) 30 halide < 20 halide < 10 halide (C) 30 halide < 20 halide > 10 halide (D) 10 halide <30 halide < 20 halide

(B) 3 0 halide < 2 0 halide < 1 0 halide