The correct answer is: <span>A. electron attraction between electron and nucleus = centripetal force of the orbiting electron
In fact, Bohr model depicts the atom as a nucleus surrounded by electrons in circular orbit around it, similar to the planets around the Sun. The centripetal force that keeps the electrons in circular motion around the nucles is provided by the electrostatic force between the electrons and the nucleus, so option A is the correct one.</span>
