Read the passage for many centuries, our understanding of atoms didest change very much from that of the ancient Greeks. In 590 BC, the Greek philosopher
Democritus wrote that storis moved around in a vend, bouncing off each other or attaching to each other. The word "atorre comes from the Greek
tomos, which means "cannot be divided " Atoms were considered the smallest things in existence. It wasst until the 19th century that these ideas
beguito be challenged by scientists such as Thomson, John Dalton, and Ernest Rutherford. Thanks to these scientists and others, our
understanding of the atom is more complex than it ever was, and it continues to evolve and change. For example, we now know that atoms are not
the smallest things in the universe, and that stoms are made up of even smaller elements such as protons, neutrons, and electrons.
Which best describes the author's attitude in the passage
1. frustrated, because our understanding of the stom is so limited
O2 smug, because our understanding of the stor has progressed significantly
3. hopeful, because our understanding of the stom is advancing
satisfied, because our understanding of the stom is complete