Which One of These Characteristics Is Not True for The \alpha

Multiple Choice

Which one of these characteristics is not true for the $\alpha$ helix?

A) There are 3.6 amino acids per turn.
B) There is a requirement for glycine every third amino acid residue.
C) A hydrogen bond forms between the carbonyl oxygen of the nth amino acid residue and the - NH group of the (n + 4) th amino acid residue.
D) Proline is typically not found in the $\alpha$ helix.
E) It is right-handed.