Answer the following question given this paragraph: 

Cells in our bodies have an intricate mechanism for the manufacture of proteins. Humans have to use other techniques in order to synthesize the same proteins in a lab. The chemistry of peptide synthesis is complicated. Both active groups on an amino acid can react and the amino acid sequence must be a specific one in order for the protein to function. Robert Merrifield developed the first synthetic approach for making proteins in the lab, a manual approach which was lengthy and tedious (and, he won the Nobel Prize in Chemistry in 1984 for his work). Today however, automated systems can crank out a peptide in a very short period of time.


Q: Robert merrifield developed the first synthetic approach for making what essential cell substances in the lab?

 Choices:

- cells

- acids

- lipids

- proteins

A:
proteins
