The correct option is **B. Polyethylene terephthalate (PET)**. ### Detailed Explanation: **1. Understanding Polyethylene Terephthalate (PET):** - **Definition:** Polyethylene terephthalate (PET) is a type of polyester that is widely used in the production of plastic bottles and containers. It is known for its excellent clarity, strength, and barrier properties against gases and moisture. - **Properties:** PET is lightweight, durable, and resistant to impact. It also has good thermal stability, making it suitable for a variety of applications, especially in the food and beverage industry. **2. Why PET is the Correct Answer:** - **Clarity:** PET has a high level of transparency, which is important for consumer products like bottled beverages, as it allows consumers to see the contents. - **Barrier Properties:** PET provides an effective barrier to oxygen and carbon dioxide, which helps in preserving the freshness and quality of the products inside the containers. This is particularly crucial for carbonated drinks, as it prevents the loss of carbonation. - **Recyclability:** PET is also highly recyclable, which is an important factor in today’s environmentally conscious market. It can be reprocessed into new bottles or other products, reducing waste. ### Why the Other Options are Incorrect or Weaker: **A. Polystyrene:** - **Properties:** Polystyrene is a versatile plastic used in a variety of applications, including packaging and insulation. However, it is not typically used for bottles due to its brittleness and lower barrier properties compared to PET. - **Clarity:** While polystyrene can be clear, it does not have the same level of clarity and strength as PET for bottle applications. **C. Polyvinyl Chloride (PVC):** - **Properties:** PVC is used in a wide range of products, including pipes, flooring, and some types of packaging. However, it is not commonly used for food and beverage containers due to concerns about leaching chemicals and its rigidity. - **Clarity:** PVC is generally opaque and does not offer the same clarity as PET, making it less suitable for applications where visibility of the contents is important. **D. Polypropylene:** - **Properties:** Polypropylene is known for its chemical resistance and is used in a variety of applications, including food containers and automotive parts. However, it does not have the same clarity and barrier properties as PET. - **Clarity:** While polypropylene can be made clear, it is often used in applications where transparency is not as critical, and it does not provide the same level of gas barrier properties as PET. ### Summary of Key Points: - **PET is the preferred choice for plastic bottles** due to its excellent clarity and barrier properties. - **It is lightweight, durable, and recyclable**, making it an environmentally friendly option. - **Other options like polystyrene, PVC, and polypropylene** do not match PET in terms of clarity and barrier effectiveness for beverage containers. ### Revision Summary: - **Polyethylene terephthalate (PET)** is primarily used for plastic bottles due to its clarity and barrier properties. - **PET is lightweight, durable, and recyclable**, making it suitable for food and beverage applications. - **Other plastics like polystyrene, PVC, and polypropylene** have limitations in clarity, strength, or safety for food contact.