To find this answer you take the mass of the carbon in the compound and divide it by the mass of the entire compound, the one closest to 40% is the correct answer.
I will do hexose for you and you can do the rest of them
mass hexose = 6*12 + 12*1 + 6*16 = 72 + 12 + 96 = 180
mass C in hexose = 6 * 12 = 72
% C in hexose = 72/180 * 100% = 40% (This may be your answer unless you have multiple answers for this one)
