Final answer:
The false statement is that α-helices and β-sheets are both incompatible with the amino acid proline, which is not true.
Step-by-step explanation:
The false statement about α-helices and β-sheets is (a) They are both incompatible with the amino acid proline. In reality, α-helices can accommodate proline residues at specific positions where the helix is interrupted, while β-sheets can contain proline residues as well.
Both α-helices and β-sheets interact with other protein elements through amino acid side chains that stick out, making statement (b) true.
Both α-helices and β-sheets contain a recurring pattern of hydrogen bonds from one peptide bond to another, which gives them their stable structure, making statement (c) true.
Lastly, α-helices and β-sheets can give rise to similar tertiary structures, making statement (d) true.