A toy manufacturer is developing a new line of biodegradable toys made from a polymer derived from natural sources. Which of the following statements best explains how the structure of this polymer differs from traditional petroleum-based plastics?

Biodegradable polymers from natural sources are made of carbon, hydrogen, and oxygen atoms arranged in chains that include many hydroxyl or carboxyl groups, which allow water molecules to attack and break the bonds. In contrast, petroleum‑based plastics have long, unbranched chains with few polar groups, making them resistant to water and microbes. Because the natural polymer has more polar sites, enzymes and microbes can recognize and degrade it more easily. For example, a plant‑derived poly(lactic acid) chain has ester bonds that hydrolyze in the presence of moisture, while a polyethylene chain remains intact. Thus, the natural polymer’s structure contains functional groups that enable biodegradation, unlike the inert structure of petroleum plastics.