Correct Answer : Option (A) - J. J. Thomson, Ernest Rutherford & James Chadwick
Electron : 02 Discovery of Electron, Proton and Neutron. Electrons were discovered by J.J. Thomson in 1897.
Proton : Observed as H⺠by Eugen Goldstein (1886). Identified in other nuclei (and named) by Ernest Rutherford (1917–1920).
Neutron : In May 1932 James Chadwick announced that the core also contained a new uncharged particle, which he called the neutron.