Which describes nuclear fusion?

starts when a neutron slams into an atom, causing the larger atom to split into two smaller atoms starts when a neutron slams into an atom, causing the larger atom to split into two smaller atoms starts when a neutron slams into an atom, causing two atoms to form one, heavier atom starts when a neutron slams into an atom, causing two atoms to form one, heavier atom starts when two atoms slam together, causing the larger atom to split into two smaller atoms starts when two atoms slam together, causing the larger atom to split into two smaller atoms starts when two atoms slam together to form one, heavier atom

starts when two atoms slam together to form one, heavier atom

Nuclear fusion starts when two atoms slam together to form one, heavier atom.

Nuclear fusion is the process in which two atomic nuclei come together to form a heavier nucleus. In this process, the combined mass of the two nuclei is slightly less than the mass of the resulting nucleus. This difference in mass is converted into energy according to Einstein's famous equation, E=mc².

Based on the given options, the correct description of nuclear fusion is:

starts when two atoms slam together to form one, heavier atom.

Nuclear fission, on the other hand, is the process of splitting a larger atom into two smaller atoms. This is the opposite of fusion and is described as:

starts when a neutron slams into an atom, causing the larger atom to split into two smaller atoms.