[单选题]
The number of molecules in one mole of(qmy 3--ra6e ;fntq5tus ob7 l a substkzj(p68qu k2u; 0w yuhance
A. depends on the molecular weight of the substance.
B. depends on the atomic weight of the substance.
C. depends on the density of the substance.
D. is the same for all substances.