For a harmonic oscillator described by

$x(t)=(0\mathrm{.}25-m)cos(4\mathrm{.}0t).$

What is its amplitude?

$1\mathrm{.}0-m$

$0\mathrm{.}25-m$

$0\mathrm{.}50*m$

$4\mathrm{.}0*m$

$0\mathrm{.}0-m$