A particle of mass $m$ is attached to a spring (of spring constant $k$) and has a natural angular frequency $\omega _ { 0 }$. An external force $F ( t )$ proportional to $\cos \omega t \left( \omega \neq \omega _ { 0 } \right)$ is applied to the oscillator. The time displacement of the oscillator will be proportional to\\
(1) $\frac { \mathrm { m } } { \omega _ { 0 } ^ { 2 } - \omega ^ { 2 } }$\\
(2) $\frac { 1 } { m \left( \omega _ { 0 } ^ { 2 } - \omega ^ { 2 } \right) }$\\
(3) $\frac { 1 } { m \left( \omega _ { 0 } ^ { 2 } + \omega ^ { 2 } \right) }$\\
(4) $\frac { m } { \omega _ { 0 } ^ { 2 } + \omega ^ { 2 } }$