Which one of the following statements is correct?

$A$: The polypeptide coil of collagen helix is strengthened by the establishment of hydrogen bonds between the $>NH$ group of the glycine residue of each strand and the $-CO$ group of the other two strands.
$R$: In the collagen helix,a locking effect also occurs with the help of proline and hydroxyproline amino acids.

Why are amino acids amphoteric in nature?

$A$: Amino acids are amphoteric in nature.
$R$: Amino acids act as electrolytes in solution.

Who classified amino acids?

$A$: Tertiary structure of protein molecules makes them biologically active.
$R$: It is the native configuration of protein molecules maintained by multiple covalent bonds only.