A spring–block system undergoes simple harmonic motion on a smooth horizontal surface. The block is now given some positive charge, and a uniform horizontal electric field to the right is switched on. As a result,
(a) the time period of oscillation will increase
(b) the time period of oscillation will decrease
(c) the time period of oscillation will remain unaffected
(d) the mean position of simple harmonic motion will shift to the right