Answer the following question given this paragraph: 

A protein is an organic compound made up of small molecules called amino acids . There are 20 different amino acids commonly found in the proteins of living organisms. Small proteins may contain just a few hundred amino acids, whereas large proteins may contain thousands of amino acids. The largest known proteins are titins, found in muscle, which are composed from over 27,000 amino acids.


Q: What are the largest known proteins called?

 Choices:

- obscures

- sporozoans

- aminos

- titins

A:
titins
