The correct response is:
In a nuclear reaction, the particles in the nucleus are changed, and one element is transformed into another. In a chemical reaction, electrons are exchanged from one or more substances to produce a different substance.
This response accurately captures the essential difference between nuclear and chemical reactions. In nuclear reactions, changes occur in the nucleus of atoms, often resulting in the transformation of elements, while in chemical reactions, the interactions primarily involve electrons and result in the formation of new substances without changing the nuclei of the atoms involved.