b
$(b)$ ${{H}_{3}}C-\underset{C{{H}_{3}}\,\,\,\,\,\,}{\mathop{\underset{|\,\,\,\,\,\,\,\,\,\,\,\,}{\mathop{CH-}}\,}}\,C{{H}_{2}}-C{{H}_{3}}+B{{r}_{2}}\to $ $\underset{\text{Major}}{\mathop{\begin{matrix}
\,\,\,\,Br \\
| \\
{{H}_{3}}C-C-C{{H}_{2}} \\
| \\
\,\,\,\,\,\,C{{H}_{3}} \\
\end{matrix}-C{{H}_{3}}}}\,$