Which statement correctly distinguishes natural and synthetic plastic sources?

• A. Natural sources include metals; synthetic sources include glass
• B. Natural sources include synthetic fibers; synthetic sources include water
• C. Natural sources include plastics directly; synthetic sources exclude oils
• D. Natural sources include plants, trees, animals, insects; synthetic sources include crude oil, coal, natural gas

Answer: (D)

The question tests where plastics’ starting materials come from: natural biomaterials versus fossil-fuel-based feedstocks. The statement that is best says natural sources include plants, trees, animals, and insects, while synthetic sources come from fossil-based resources like crude oil, coal, and natural gas. This captures the usual distinction: many natural polymers come from biological materials (such as cellulose from plants, proteins from animals, or natural resins), whereas most common modern plastics are made from monomers derived from fossil fuels after chemical processing. The other options mix up what plastics originate from—for example, metals or glass aren’t plastic sources; water isn’t a feedstock for plastics; and plastics are not directly sourced from oils in a natural sense but are produced from petrochemical processes using oils, natural gas, or coal.