The correct answer is D. All the above.
Alexander Parkes, a Scottish chemist, prepared a hard material by mixing camphor and alcohol with nitro cellulose and called it, as Parkesite. This was the first plastic to be produced commercially.
Dr. L. Bakeland, a Belgian scientist, prepared a product known as Bakelite. Bakelite is a thermosetting plastic, which means that it cannot be melted and remolded once it has been formed. It is used in a variety of applications, including electrical insulation, cookware, and jewelry.
Pollark, an Austrian scientist, prepared a substance from urea and formaldehyde and called it Plastic. This substance is also known as urea-formaldehyde resin. It is a thermosetting plastic that is used in a variety of applications, including adhesives, coatings, and foams.
In conclusion, all of the statements in the question are correct. Alexander Parkes, Dr. L. Bakeland, and Pollark all made significant contributions to the development of plastic.