The right answer is polysaccharides (starch).
The Lugol test is positive !
In both starch and glycogen molecules, glucose units linked by alpha 1-4 osidic bonds form helical chains of amylose, on which short chains of the same constitution branch through alpha 1-6 osidic bonds. In starch, these branches are present about every thirty glucose residues while in glycogen, they are present about every ten residues.
In the presence of iodine, the starch is colored blue-violet while the glycogen is colored mahogany brown.
In the cells, the starch forms grains of paracrystalline structure of a few microns in diameter observable under optical microscope without particular coloration or after staining with diluted Lugol. Their observation with a polarizing microscope is also interesting.
The other reactions are negative.
