What characteristic differentiates modified natural plastics from natural plastics?

Modified natural plastics are characterized by having undergone chemical alterations from their original form. This process can involve the addition of various substances or the alteration of the molecular structure to enhance properties such as strength, durability, or flexibility.

In contrast to natural plastics, which maintain their original composition derived from natural sources like plants, modified natural plastics are designed to improve performance in specific applications, making them more versatile and suitable for a wider range of uses.

The other choices do not accurately represent the key characteristic needed for differentiation. For instance, while some modified natural plastics may have synthetic components, they are not always purely synthetic. The assertion that they are derived from petroleum is also misleading, as modified natural plastics can still retain their origins from natural sources even after chemical modifications. Finally, the claim that they contain zero carbon compounds is inaccurate, as both natural and modified plastics typically contain carbon as a fundamental element of their chemical structure.