The correct option is **C. Polyethylene terephthalate (PET)**. ### Detailed Explanation: 1. **Understanding the Properties of PET**: - **Clarity**: PET is known for its excellent optical clarity, which makes it ideal for applications where visibility of the contents is important, such as in plastic bottles for beverages. - **Moisture Resistance**: PET has a low permeability to moisture, which helps in preserving the quality of the contents, especially liquids. This property is crucial for food and beverage packaging, as it prevents spoilage and maintains freshness. 2. **Applications of PET**: - PET is widely used in the production of plastic bottles, containers, and packaging materials. Its combination of strength, lightweight nature, and recyclability makes it a preferred choice in the beverage industry, particularly for soft drinks and water bottles. 3. **Why Other Options Are Incorrect**: - **A. Polyethylene (PE)**: - While polyethylene is a versatile plastic used in many applications, it does not have the same level of clarity as PET. It is often used for bags, films, and containers but lacks the moisture barrier properties that PET offers for liquid storage. - **B. Polyvinyl chloride (PVC)**: - PVC is used in a variety of applications, including pipes and vinyl siding, but it is not typically used for food and beverage containers due to concerns about leaching chemicals and its rigidity. It also does not provide the same clarity as PET. - **D. Polystyrene (PS)**: - Polystyrene is often used for disposable cutlery, plates, and foam containers. While it can be clear, it is not as moisture-resistant as PET and is more brittle, making it less suitable for bottles that need to withstand pressure and impact. ### Summary of Key Points: - **PET** is the polymer of choice for plastic bottles due to its **clarity** and **moisture resistance**. - **Polyethylene (PE)**, **PVC**, and **Polystyrene (PS)** do not match PET's properties for this specific application. - PET is also **recyclable**, which adds to its appeal in sustainable packaging solutions. ### Revision Summary: - **Correct Answer**: C. Polyethylene terephthalate (PET) - **Key Properties of PET**: Excellent clarity, moisture resistance, and recyclability. - **Common Uses**: Primarily in beverage bottles and food containers. - **Comparison with Other Polymers**: PE, PVC, and PS are less suitable due to clarity, moisture resistance, and safety concerns.