Which set of three elements can bond together to form the backbone of most organic compounds?

• A. $C$, $H$, and $O$
• B. $\mathrm{Na}$, $\mathrm{Cl}$, and $K$
• C. $N$, $O$, and $\mathrm{Cl}$
• D. $\mathrm{Mg}$, $\mathrm{Ca}$, and $\mathrm{Fe}$

Answer: (A)

Verified step by step guidance

1. Understand that the backbone of most organic compounds is primarily made up of carbon atoms due to carbon's unique ability to form four stable covalent bonds, allowing for complex and diverse molecular structures.
2. Recognize that hydrogen is almost always bonded to carbon in organic molecules, completing carbon's valence shell and forming hydrocarbons and their derivatives.
3. Identify oxygen as a common element bonded to carbon and hydrogen in many organic functional groups such as alcohols, ethers, carbonyls, and carboxylic acids, contributing to the diversity of organic compounds.
4. Note that the other sets of elements listed (Na, Cl, K; N, O, Cl; Mg, Ca, Fe) are either metals, halogens, or less commonly part of the organic backbone, and thus do not form the primary framework of organic molecules.
5. Conclude that the set of elements C (carbon), H (hydrogen), and O (oxygen) are the fundamental elements that bond together to form the backbone of most organic compounds.