Most organic molecules contain a combination of carbon, hydrogen, nitrogen, and/or oxygen. Ocasionally, the amino acids in the oragnic molecules will also have other elements in them. An example of this is iron, copper, sulfur, and phosphorus. Any other elements are not very likely to be included in the structure of an organic molecule. So, if any of the answer choices you were given are not any of the elements I just listed, that is the answer to your question.
