What is a petroleum by-product known for its excellent sealing properties?

The correct answer is paraffin, which is a petroleum by-product recognized for its excellent sealing properties. Paraffin is commonly used in various applications due to its ability to create effective seals by forming a barrier that prevents the passage of liquids or gases. Its waxy composition allows it to conform to surfaces, providing airtight and watertight seals.

Paraffin is often utilized in industries that require reliable sealing solutions, such as in candles, coatings, and even food preservation. Its chemical stability and low reactivity enhance its suitability for these uses, as it resists degradation and maintains its sealing properties under various conditions.

Other options like wax, grease, and oil may have sealing characteristics but do not match paraffin's specific benefits for sealing applications. Wax can refer to a broader category of substances and may not provide the same level of sealing effectiveness. Grease typically serves as a lubricant rather than a sealing agent, while oil is primarily a fluid used for lubrication and may not provide the same sealing efficiency.