Natural plastics are exemplified by which of the following?

Natural plastics are derived from organic sources and exhibit polymeric properties, making them essential in various applications. Finger nails and hair are both composed of keratin, a natural protein that has properties similar to that of synthetic plastics. This keratin can be molded and shaped upon heating, similar to how synthetic plastics function, and showcases properties like durability and flexibility.

The other choices do not match the characteristics of natural plastics. Cellulose is a natural polymer but when combined with styrene, which is a synthetic compound, it doesn't represent a purely natural plastic. Bamboo and metal do not fall under the category of plastics, as metal is a metal and bamboo is a natural material but not a plastic. Wood, while natural, is not classified as a plastic, and glass is an inorganic substance. Thus, finger nails and hair is the only option that aligns with the definition of natural plastics.