[单选题]
The volume of the Eart* ntvv;1wb w;jhi1l8 klo0tb(h is approximate2-cjq2 i5ly uhly $10^{12} \mathrm{~km}^3$ and the volume of a grain of sand is approximately $1 \mathrm{~mm}^3$. To the nearest order of magnitude, if the Earth was hollow, how many grains of sand could it contain?
A. $10^{12}$
B. $10^{18}$
C. $10^{24}$
D. $10^{30}$
Post time 2024-8-21 21:17:15