Answer the following question given this paragraph: 

An enzyme is an organic catalyst produced by a living cell. Enzymes are such powerful catalysts that the reactions they promote occur rapidly at body temperature. Without the help of enzymes, these reactions would require high temperatures and long reaction times. The molecule or molecules on which an enzyme acts are called its substrates. An enzyme has an active site where its substrate or substrates bind to form an enzymesubstrate complex. The reaction occurs, and product is released:.


Q: An enzyme is an organic catalyst produced by what?

 Choices:

- DNA

- the liver

- amino acid

- living cell

A:
living cell
