Understand the definition of organic molecules: Organic chemistry primarily studies compounds that contain carbon atoms bonded to other elements.
Recall that while elements like sulfur (S), oxygen (O), and nitrogen (N) are common in many organic compounds, they are not present in every organic molecule.
Recognize that carbon (C) is the fundamental element that forms the backbone of all organic molecules, making it essential and always present.
Note that organic molecules are characterized by carbon-hydrogen (C-H) bonds, which distinguishes them from inorganic compounds.
Conclude that the element present in all organic molecules is carbon (C), as it is the defining element of organic chemistry.