There are four major types of macromolecules, and each type has specific functions and characteristics. Proteins are made of amino acids and function as enzymes, receptors, hormones, signals, and receptors. Lipids are made of fatty acids and glycerol and function as membrane components and energy storage. Carbohydrates are made of monosaccharides and function as energy storage. Nucleic acids are made of nucleotides and provide genetic information for organisms.

All four types of macromolecules are organic compounds. Which of the following statements describes a difference between organic and inorganic compounds?
(A) Only organic compounds contain oxygen.
(B) Only organic compounds contain covalently bonded carbon atoms.
(C) Only organic compounds contain hydrogen bonds.
(D) Only organic compounds contain ionizing chemical groups.