Unicellular organisms are living things made up of only one cell. For example, bacteria and yeast are unicellular. Multicellular organism are made up of more than one cell. Some examples of a multicellular organisms are humans and animals.
Answer:

Option B is correct.
Explanation:
There are <u>thousands</u> of proteins and only 20 amino acids.
Hope I helped!
Best regards! :D
~