Which of the following materials is made of natural polymers?

Starch is the correct answer because it is a carbohydrate consisting of a large number of glucose units joined by glycosidic bonds. Starch is produced by many green plants and serves as a form of energy storage. It occurs naturally and is found in significant amounts in foods such as potatoes, corn, and wheat. Since it is derived from natural sources and is a polymer made from repeating units of glucose, it qualifies as a natural polymer.

In contrast, cellulose, although also a natural polymer and a primary component of plant cell walls, is not the answer here since the question might be more focused on the specific context of common energy storage polymers related to food. Nylon and polyester, on the other hand, are synthetic polymers created through chemical processes and are not natural polymers at all. These synthetic materials are made from petrochemical sources and involve complex manufacturing processes, which distinctly separates them from natural polymers like starch.