C: incorrect. It caught you. There is only 1 molecule of C6H12O6 that you are given. That means there are 24 atoms in all for that glucose. Don't worry. I got caught as well. I was about to write a note saying that it should be the answer. It shouldn't.
A: has three atoms per molecule. There are 6.02 * 10^23 molecules - an incredibly large number which becomes 3 times its size when you ask about this in moles. Still A, large as it is , is not the answer.
B: H2O2 has 4 atoms per molecule. 4 mols have 4 * 6.02*10^23 atoms in a mol of H2O2. Read this sentence and A very carefully. There is 1 mol of CO2 which equals 3 * 6.02*10^23 atoms in 1 mol of CO2 which has 6.02 * 10^23 molecules per mole. Be sure you understand the difference.
B is the answer.
D and E are parts of a mol. They are bigger than C (much) but much smaller than A or B.
The molecular weight has nothing to do with your answer. Please read B and A until you understand them.