Which ONE of the following statements is FALSE ? A. Secondary structural elements fold in three dimensions to result in the final native protein. B. Some proteins do contain only alpha-helices and no beta-strands. C. Membrane proteins are hydrophilic on the surfaces that are in contact with the membrane. D. Some proteins do contain only beta-strands and no alpha-helices. E. The core of a protein is usually densely packed and water is excluded.