IUPAC name of the compound with the molecular formula ${\mathrm{C}}_4{\mathrm{H}}_9\mathrm{Br}$ and least possible boiling point is 

• Tert-Butyl bromide (also known as 2-bromo-2-methylpropane) is a chemical having the formula ${\left({\mathrm{CH}}_3\right)}_3\mathrm{C}-\mathrm{Br}$. As the number of branches increases Boiling point Decreases.

Hence, the correct answer is option (A) 2–Bromo–2–methylpropane.