An amino acid residue that is not part of the active site of an enzyme and does not interact with the ligand is nevertheless critical for ligand binding and is highly conserved. How can this be explained?

A) This residue is critical for the correct folding and the placement of ligand-binding site residues.
B) The residue helps with restricting the access of water to the ligand-binding site.
C) This residue can affect the chemical properties of the residues in the ligand-binding site.
D) All of the above.