Q. The known forces of nature can be divided into four classes, viz, gravity, electromagnetism, weak nuclear force and strong nuclear force. With reference to them, which one of the following statements is not right?
A. Gravity is the strongest out of the four forces
B. Strong nuclear force holds protons and neutrons inside the nucleus of an atom
C. Weak nuclear force causes radioactivity
D. Electromagnetism acts only on particles with an electric charge