Answer:
The correct answer is "that atoms are very small".
Step-by-step explanation:
Comparing the number of atoms in a penny, with the number of people on Earth is used to illustrate that atoms are very small. This comparison helps the reader to think themselves as if they would be atoms, they would be so small that a copper coin the size of a penny would be the Earth for them. For instance, the atoms are so small that a human is the size of the Sun for them.