Pick up the correct statement from the following: A. The substance which consists of one primary chemical, is known as monomer B. The polymer consists of thousands of monomers joined together C. The polymer molecule is called macro-molecule D. All the above

The substance which consists of one primary chemical, is known as monomer
The polymer consists of thousands of monomers joined together
The polymer molecule is called macro-molecule
All the above

The correct answer is D. All of the above.

A monomer is a small molecule that can be linked together with other monomers to form a polymer. A polymer is a large molecule that is made up of many monomers. A macro-molecule is a very large molecule, and polymers are examples of macro-molecules.

For example, polyethylene is a polymer that is made up of many ethylene monomers. Ethylene is a small molecule with the formula $C_2H_4$. Polyethylene is a large molecule with the formula $(C_2H_4)_n$, where $n$ is a large number.

Polymers are found in many different materials, including plastics, rubber, and textiles. They are also found in living things, such as proteins, DNA, and RNA.