Which describes nuclear fusion?(1 point) Responses starts when two atoms slam together to form one, heavier atom starts when two atoms slam together to form one, heavier atom 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