Six carbons CH2OH CH2OH CH2OH CH2OH C=0 C=0 C=0 C=0 H-C-OH HO-C-H H-C-OH HO-C-H H-C-OH H-C-OH HO-C-H HO-C-H H-C-OH H-C-OH H-C-OH H-C- OH CH2OH CH2OH CH2OH CH2OH D-Psicose D-Fructose D-Sorbose D-Tagatose D-Ketoses (b)