Which biological molecule is smallest due to being a subunit rather than a macromolecule? protein starch nucleic acid glucose lipid?

The right option is; glucose

Glucose is the  biological molecule that is smallest due to being a subunit rather than a macromolecule.

Glucose is a simple sugar (monosaccharide), a sub unit of carbohydrates. Glucose is the most significant energy source  in all organisms. It is the most abundant carbohydrate and it is mainly present in foods rich in carbohydrates, such as rice, potatoes, and fruit. Glucose is also produced by plants and most algae during photosynthesis.