Which of the following is a primary alkyl halide ?

A primary alkyl halide is an alkyl halide (haloalkane) in which the halogen atom $\left(F, Cl, Br or I\right)$ is linked to a primary carbon.

The structures for given options are below.

Isobutyl bromide:- ${\mathrm{CH}}_3-\mathrm{CH}\left({\mathrm{CH}}_3\right)-{\mathrm{CH}}_2-\mathrm{Br}$

neo-Pentyl chloride:- ${\mathrm{CH}}_3-\mathrm{C}{\left({\mathrm{CH}}_3\right)}_2-{\mathrm{CH}}_2-\mathrm{Cl}$

iso-pentyl bromide:- ${\mathrm{CH}}_3-\mathrm{CH}\left({\mathrm{CH}}_3\right)-{\mathrm{CH}}_2-{\mathrm{CH}}_2-\mathrm{Br}$

In all the alkyl halides, halogen is attached to primary carbon.