Answer:
Option 3 = i.e. If you add the masses of all the products after fission, they are LESS than the mass of the reactants
Step-by-step explanation:
Nuclear fission: Is the process in which the nucleus of radioactive element with higher mass undergoes fission and get into fragment of smaller mass with release of high energy.
The products of the nuclear fission are the fragment of smaller nuclei.
For example, larger nucleus that of uranium split into two small nuclei along with some neutrons, energy and gamma rays.
The mass of the original atom always more than the sum of the atomic masses of the atoms produce by fission. The reason is neutrons and kinetic energy lost, and upon cooling we get product masses less than original.