Hi!
The correct answer would be C
The key difference between the two types of reactions is that nuclear reaction involves a change in the nucleus of the atom(s) involved in the reaction, where as atoms in chemical reactions do not undergo any change in their nucleus.
Option A and B both deal with characteristics that pertain to only nuclear reactions, as both nuclear fusion and fission involve a change in the nuclear state of the initial elements.
Option D deals with the characteristic that pertains only to chemical reactions, which involve the transfer -gain or loss of electrons.
However, both of these types of reactions may be exothermic, with the capacity to release this energy as light, or heat.
Hence, Option C is correct
Hope this helps!
