Seals are comprised of what?

The correct choice highlights that seals are commonly made from high-grade flexible rubber compounds. This material is utilized because of its ability to provide an effective barrier against fluids, gases, and contaminants, ensuring a secure fit and preventing leaks in various applications, such as automotive engines or plumbing systems. The flexibility of rubber allows it to conform tightly to surfaces, which is essential for maintaining a seal under various pressures and temperatures.

In contrast, while epoxy impregnated fiberglass and vulcanized aluminum are materials used in other contexts, such as structural or high-performance applications, they do not possess the necessary flexibility or sealing properties required for effective seals. Cork, while it has been historically used in some sealing applications due to its compressibility and resistance to moisture, is not as versatile or durable as high-grade rubber compounds for modern sealing purposes.