Correct Response: D. Each carbon atom is able to form four covalent bonds. This allows carbon to form molecules with diverse characteristics that include the ability to form carbon chains of differing lengths, double and triple bonds, and bonds with a variety of different functional groups. Although oxygen (A) is able to react with a large variety of different molecules, in most cases each oxygen atom can form only two covalent bonds. The size of phosphorus (B) contributes to its ability to form more covalent bonds than nitrogen (C) or even carbon. However, the structure of phosphorus and nitrogen do not allow the formation of the variety of chains or bonds and functional groups demonstrated by carbon-based molecules.
