What is the value of cube after the following code executes?

double cube, side;

side $=5\mathrm{.}0$;

cube $=$ pow $($ side, $3\mathrm{.}0)$;

$0$

$15\mathrm{.}0$

$125\mathrm{.}0$

$25\mathrm{.}0$

unknown