Design a protein with a specific function by describing its primary, secondary, tertiary, and quaternary structures.

• A. A protein with a primary structure of random amino acids, secondary structure of beta sheets, tertiary structure forming a linear shape, and no quaternary structure.
• B. A protein with a primary structure of hydrophilic amino acids only, secondary structure of alpha helices, tertiary structure forming a fibrous shape, and quaternary structure with three subunits.
• C. A protein with a primary structure of identical amino acids, secondary structure of random coils, tertiary structure forming a flat shape, and quaternary structure with multiple identical subunits.
• D. A protein with a primary structure of alternating hydrophobic and hydrophilic amino acids, secondary structure of alpha helices, tertiary structure forming a globular shape, and quaternary structure with two subunits for binding.

Answer: (D)