How do primary, secondary, and tertiary structures of proteins relate to one another?

• A. Primary structure determines amino acid sequence, secondary forms local structures, tertiary gives overall 3D shape.
• B. Primary structure provides the 3D shape, secondary arranges in helices and sheets, tertiary is the sequence.
• C. Secondary structure is made up of tertiary structures, primary is unrelated.
• D. Primary and secondary structures are not related, only tertiary determines function.

Answer: (A)