Answer: b. Democritus
Explanation:
The greek philospher Democritus around 400 B.C proposed first atomic theory. He proposed the fact that the world is made of two things such as void (empty space) and the tiny particles called as atoms. He said that the atoms are indestructible, small and invisible. These atoms cannot be broken as they are the smallest particles. The atoms combine to form molecules, ions, rocks and other entities.
