(d)
Since,$s^{3} \propto v\ \Rightarrow \frac{ds}{dt} = ks^{3}$…….(i)
$\Rightarrow \ \ \ \ \ \ \ \frac{d^{2}s}{dt^{2}} = 3ks^{2}\frac{ds}{dt\ }$
$\Rightarrow \ \ \ \ \ \ \ \ \frac{d^{2}s}{dt} = 3k^{2}s^{5}\ \ \ \ \ \ \ \ \left\lbrack from\ Eq.(i) \right\rbrack$
Hence, acceleration of particle is proportional to $s^{5}$.