Correct option is (a)
Gypsum is added to Portland cement to avoid "flash setting," which allows for a longer working period. Gypsum delays the setting of cement, allowing it to solidify properly.
Nylon is a man-made synthetic fibre generated from petrochemicals that is widely utilised in the fashion industry. Hence, Nylon is a textile fabric.
Teflon is a chemical compound composed of carbon and fluorine atoms. It was invented in the 1930s and offers a nonreactive, nonstick, and nearly frictionless surface. Teflon-coated cookware is easy to use and clean because of its nonstick surface.
Crookes glass contains Cerium oxide (CiO2), which absorbs UV rays from the sun very effectively. It's utilised in the production of eyeglass lenses.
