The correct choice is d, that is, the number of molecules.
Explanation:
A mole is defined as the mass of substance divided by its molecular mass. A mole of table sugar and a mole of vitamin C do not have the same mass. Since volume corresponds directly to mass, differences in mass imply differences in volume as well.
Vitamin C and sugar are compounds consisting of different elements combined in specific molecular ratios. Consequently, they differ in atomic composition, mass, and volume.
One mole always contains 6.023 × 1023 molecules (Avogadro's number), which is the same for any substance. Therefore, one mole of vitamin C and one mole of table sugar have an identical number of molecules.
