Answer: The atom is mostly empty space.
Explanation:
Before to Rutherford, the accepted model for the atom was Thomson's model:
The atoms were a positive sphere, with electrons occupying space in it".
This was called the "plum pudding model".
Then came Ernest Rutherford, and he created a model where the atoms are mostly empty space (void) with a positive charged nucleus (really compressed in the center), and the electrons were orbiting around it.
Then the correct option is that the atom is mostly empty space.
