The correct answer is $\boxed{\text{(D) Pt}}$.
Platinum is a noble metal that is often used as a catalyst in chemical reactions. It is particularly effective in hydrogenation reactions, which are reactions in which hydrogen is added to another molecule. In the hydrogenation of oils, platinum is used to convert unsaturated fats into saturated fats. This process is used to improve the stability and shelf life of oils, and it is also used to produce margarine and shortening.
Nickel is also a metal that is sometimes used as a catalyst in hydrogenation reactions. However, it is not as effective as platinum, and it is more likely to contaminate the product. Lead and copper are not typically used as catalysts in hydrogenation reactions.
Here is a brief explanation of each option:
- Option (A), nickel, is a metal that is sometimes used as a catalyst in hydrogenation reactions. However, it is not as effective as platinum, and it is more likely to contaminate the product.
- Option (B), lead, is a heavy metal that is not typically used as a catalyst in hydrogenation reactions. It is a toxic substance that can be harmful to human health.
- Option (C), copper, is a metal that is sometimes used as a catalyst in other types of chemical reactions. However, it is not typically used as a catalyst in hydrogenation reactions.
- Option (D), platinum, is a noble metal that is often used as a catalyst in chemical reactions. It is particularly effective in hydrogenation reactions, which are reactions in which hydrogen is added to another molecule. In the hydrogenation of oils, platinum is used to convert unsaturated fats into saturated fats. This process is used to improve the stability and shelf life of oils, and it is also used to produce margarine and shortening.