- NaCl (sodium chloride): This is an inorganic compound, commonly known as table salt. It is composed of sodium and chlorine ions and does not contain carbon.

- H2O (water): This is an inorganic compound that is essential for life. It is composed of hydrogen and oxygen atoms and does not contain carbon.

- C6H12O6 (glucose): This is an organic compound, specifically a monosaccharide sugar. It is composed of carbon, hydrogen, and oxygen atoms and is the primary source of energy for cells.

- O2 (oxygen): This is an inorganic compound, specifically a diatomic gas. It is composed of two oxygen atoms and is essential for respiration and various other biological processes.

Therefore, only C6H12O6 (glucose) is an organic compound among the given options.