In a `S_(N)2` substitution reaction of the type
`R-Br+Cl^(-) overset("DMF")toR-Cl+Br^(+)`
which one of the following has the highest relative rate?

Options

A. `CH_(3) - overset(CH_(3))overset(|) underset(CH_(3))underset(|)( C) - CH_(2) Br`
B. `CH_(3) CH_(2) Br`
C. `CH_(3) - CH_(2)- CH_(2) Br`
D. `CH_(3) - underset(CH_(3))underset(|)( C) H - CH_(2) Br`

Answer

B

Explanation

For `S_(N^2)` reaction these should be low steric hinderance for better reactivity.