Which particles that make up an atom are involved in nuclear reactions?
A. protons only
B. protons and neutrons
C. electrons only
D. electrons and neutrons

Protons and neutrons are involved in most nuclear reactions. In alpha decay two protons and two neutrons are emitted from the atom's nucleus. In nuclear fission, an atom’s nucleus is split forming two new atoms. In nuclear fusion, the nuclei of two atoms combine to form a single atom.