James Chadwick discovered the neutron in 1932. This discovery came after Ernest Rutherford’s nuclear model of the atom, which was proposed in 1911, and following J.J. Thomson’s discovery of the electron in 1897. Chadwick's work provided further insight into the structure of atoms by revealing the existence of a neutral particle in the nucleus.
Given this timeline, the correct choice from your options is:
After Thomson and Rutherford.