单选题 The primary purpose of the passage is to

• (A) expose the fragile nature of the foundations on which bioengineering research rests
• (B) argue that bioengineering is ultimately infeasible as a means of manufacturing plastic
• (C) argue that the advances in organically-based plastic manufacture cannot solve environmental issues
• (D) explain the reasons for and objectives of current research on the development of organically-based plastic manufacture
• (E) describe the nature of the organic plastic manufacturing process