A molecule that cannot act as a target for drug function in the body is:

1. Carbohydrates

2. Lipids

3. Vitamins

4. Proteins

HINT: Vitamins are not drug targets.
Explanation:
A drug target is a molecule in the body, usually a protein, that is intrinsically associated with a particular disease process and that could be addressed by a drug to produce a desired therapeutic effect.
The macromolecules chosen as drug targets are carbohydrates, lipids, proteins, and nucleic acids.
These drug targets are also known as target molecules, as they are key molecules that are involved in certain metabolic pathways that result in specific diseases.