What characterizes an organic compound?

An organic compound is primarily characterized by the presence of carbon atoms, typically bonded to hydrogen and possibly other elements such as oxygen, nitrogen, sulfur, or phosphorus. The correct answer highlights that an organic compound is a compound of carbon and another element or radical, which encompasses a broad range of substances beyond just simple hydrocarbons.

This definition captures the complexity and diversity of organic chemistry, where carbon's ability to form stable covalent bonds allows it to participate in a myriad of chemical structures, including chains, rings, and branched configurations. By including "another element or radical," the answer recognizes that organic compounds can have functional groups that influence their properties and reactions.

While it is accurate that many organic compounds contain both carbon and hydrogen, and while some may even be solid at room temperature, these are not sufficient criteria alone to classify a compound as organic. Additionally, the definition explicitly excludes any substance that contains no carbon atoms, as such compounds would fall under the category of inorganic chemistry. Thus, the distinction made in the correct answer is essential to understanding the foundational principles of organic chemistry.