Despite being cheap, versatile, and easy to produce, ______ they are made from nonrenewable petroleum, and most do not biodegrade in landfills. Which choice completes the text so that it conforms to the conventions of Standard English?
A. there are two problems associated with commercial plastics:
B. two problems are associated with commercial plastics:
C. commercial plastics' two associated problems are that
D. commercial plastics have two associated problems.