A Protein Is Highly Unlikely to Have Both $\phi$ And $\Psi$ Angles Equal to Zero Degrees Due To:
A) Steric Hindrance

Multiple Choice

A protein is highly unlikely to have both $\phi$ and $\Psi$ angles equal to zero degrees due to:

A) steric hindrance between the side chain and the peptide backbone.
B) polarity differences between adjacent side chains.
C) hydrophobic interactions between adjacent side chains.
D) steric hindrance between adjacent side chains.
E) too few van der Waals contacts for proper folding.