Which substance is made of polymers? a. marble b. protein c. salt d. steel

The answer is B, protein.

Option B) is the correct answer.

Explanation:

A polymer is defined as a molecule which has 'n' number of monomer units.

For example, is a poly ethene polymer.

Similarly, proteins are also polymers as they are made up of amino acids and contain number of repeated units just like polymers.

Thus, we can conclude that protein is made of polymers.

a corroding iron, if that's one of your choices