What binds in the "oxyanion hole" during chymotrypsin catalysis?

A. the imidazole group of the active site His
B. the nucleophilic negatively charged oxygen on the active site Ser
C. the negatively charged oxygen on the tetrahedral intermediate
D. the oxygen atom of the substrate's carbonyl (C=O) group with the double bond to the O
E. the hydrophobic or aromatic R group of residue preceding the peptide bond to be cleaved
F. the carboxylate oxygen of the active site Asp