Fiber obtained by chemical treatment of wood pulp is called _______.
A. natural silk
B. rayon
C. nylon
D. polyester

Hint:Fiber is a type of carbohydrate specifically complex carbohydrate. They are used primarily in making paper and clothes. Wood pulp is a fibrous material which is obtained by separating cellulose fibers from wood.

Complete step by step answer:
The given substances are polymers of several substances obtained from nature resources. Some are obtained as crude and others are obtained after chemical and mechanical treatment of the natural products. Let us evaluate the given set of options and their preparations.
A. Natural silk. It is fabric material which is composed mainly of fibroin. Fibroin is a protein fiber obtained from the cocoons of the larvae of mulberry silkworm. Silk possesses strength and is known as the strongest natural fibers.
B. Rayon. Rayon is manufactured or fabricated from regenerated cellulose fiber. The wood pulp is used as the crude material to produce rayon. It is made from filtered cellulose which is chemically changed over into a soluble fiber complex compound.
C. Nylon. Nylon is a polymer which is prepared from condensation of an acid monomer and an amine monomer. It is a strong and light synthetic fiber. No plant or animal raw materials are used to produce this type of fiber.
D. Polyester. As the name suggests it is also a polymer compound. It is the product obtained by condensation of an acid and an alcohol monomer. The repeating unit of the acid and alcohol leads to several polyester bonds. The starting materials used are terephthalic acid and ethylene glycol.
Hence, fiber obtained by chemical treatment of wood pulp is called rayon i.e. option B is the correct answer.

Note: Rayon could be a man-made texture mixed from cotton, wood mash, and other normal or manufactured filaments. Since it is so comfortable and cooling to wear, rayon is particularly used for sportswear and summer dresses.