The boiling point of (A) alcohol is highest due to 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. ∴ The correct decreasing order of boiling point in given compound is A>B>D>C‌. ‌