Suppose 3 neutrons are released by an atom of u-235 in the first stage of a fission chain reaction. each of these neutrons has enough energy to cause another fission reaction in another nucleus of u-235, releasing more neutrons. and if all of those 2nd stage neutrons cause other nuclei to fission in a 3rd stage, how many total u-235 atoms will have undergone fission after these 3 stages of the chain reaction? a. 27 b. 9 c. 11 d. 12