Here's why:

* Carbohydrates: Composed of carbon, hydrogen, and oxygen (CHO).

* Fats (lipids): Also composed of carbon, hydrogen, and oxygen, but with a higher proportion of hydrogen.

* Proteins: Made up of chains of amino acids, which contain carbon, hydrogen, oxygen, and nitrogen (CHON).

* Amino acids: The building blocks of proteins.

* Oil: A type of fat that's liquid at room temperature.

CO2 only contains carbon and oxygen. It's a simple inorganic molecule, not a complex organic molecule like the ones listed above.