Explanation

Starch is a polysaccharide made of long chains of glucose units, which places it squarely in the carbohydrate category of biomolecules. Plants store excess glucose as starch in seeds, tubers and roots as an energy reserve. Proteins are made of amino acids, lipids of fatty acids and glycerol, and nucleic acids of nucleotides — none of which describes starch. Hence option B is correct.