Which one of the following statements about an oscillating mechanical system at resonance, when it oscillates with a constant amplitude, is not correct? A The amplitude of oscillations depends on the amount of damping. B The frequency of the applied force is the same as the natural frequency of oscillation of the system. C The total energy of the system is constant. D The applied force prevents the amplitude from becoming too large. The answer is A. Can someone please explain why A in incorrect, and why D is correct? Thank you very much.