$x=a \sin (\omega t+\pi t 4)$
at $t=0, x=5$
$5=a \sin \pi / 4$
$5=a \sin 45^{\circ} \Rightarrow a=5 \sqrt{2}$
Maximum acceleration $\mathrm{A}_{\mathrm{max}}=\mathrm{a} \omega^{2}$
$=500\sqrt{2}\,m/s^2$

where $x=$ displacement at time $t$
$\omega =$ frequency of oscillation
Which one of the following graphs shows correctly the variation $a$ with $t$ ?
Here $a=$ acceleration at time $t$
$T=$ time period