When a body vibrates under a periodic force, the vibrations of the body are:
(a) natural vibrations
(b) Damped vibrations
(c) Forced vibration
(d) Resonant vibrations
When a body vibrates under a periodic force, the vibrations of the body are:
(a) natural vibrations
(b) Damped vibrations
(c) Forced vibration
(d) Resonant vibrations

The vibrations of a body are forced vibrations when it vibrates under a periodic force.