Answer:
C. thioesters
Explanation:
Lipids and nucleic acid are macromolecule or biomolecules. Hence option A and B are incorrect.
Carbon is an element. Hence option D is incorrect.
Thioesters are functional groups. Hence option C is correct.
Thioesters are just like esters except they have a S atom replacing one atom of O. Thioesters are formed by the reaction of a carboxylic acid with a thiol group.
