Protein A will fold into its native state only when protein B is also present in the solution. However, protein B can fold itself into native confirmation without the presence of protein A. Which of the following is true?

• A. Protein B serves as precursor for protein A
• B. Protein B serves as molecular chaperon for protein A
• C. Protein B serves as ligand for protein A
• D. Protein B serves as structural motif for protein A