The molecules in both (A) and (B) contain the –OH group and can hydrogen bond to other identical molecules. The molecules in (C) and (D) cannot hydrogen bond to other identical molecules because they do not contain the –OH, –NH, or H–F bond. The molecule in (D) cannot hydrogen bond to the molecule in (C) and there is no molecule below (D. The molecule in (C) cannot hydrogen bond to the molecule in (D) but it can hydrogen bond to the molecule in (B).