Which of the following correctly describes what happens when an atomic bomb explodes? select the correct answer below: small pieces of fissionable material are joined and form a body with a mass greater than the critical mass, the relative number of neutrons escaping decreases, and a chain reaction and explosion result. large pieces of fissionable matter are brought together quickly and form a body with a mass smaller than the critical mass, the relative number of escaping neutrons increases, and a chain reaction and explosion result. small pieces of fissionable material are brought together to form a body with a mass smaller than the critical mass, the relative number of escaping neutrons increases, and a chain reaction and explosion occur. large pieces of fissionable matter are brought together quickly and form a body with a mass larger than the critical mass, the relative number of escaping neutrons decreases, and a chain reaction and explosion result.