The boiling point of $(\mathrm{A})$ alcohol is highest due to $\mathrm{H}$-bonding.
Out of primary (B), secondary (D) and tertiary amines (C), the boiling point in decreasing order is
Primary amine $>$ Secondary amine $>$ Tertiary amine
as intermolecular association decreases in same order, being highest in primary amine and least in tertiary amine due to steric hindrance.
$\therefore$ The correct decreasing order of boiling point in given compound is
A $>$ B $>$ D $>$ C.