Due to the incredible size of the universe, our search for extraterrestrial life will probably be limited to within our
A) Local Group of galaxies
B) Local Supercluster of galaxies
C) Milky Way galaxy
D) solar system
Question 2
The two families of fundamental particles out of which all ordinary matter is made are
A) protons and neutrons.
B) leptons and quarks.
C) electrons and neutrinos.
D) quarks and neutrinos.
E) leptons and photons.