Consider the implementation of the C function named pcdif below:

float pcdif$($ float actual, float base$)\{$ return $($actual $-$ base$)/$ base $*100\mathrm{.}0$; $\}$

Which of the following can be used as the function prototype for pcdif?

a$.$ float pcdif$($ actual, base $)$;

b$.$ float pcdif$(,)$;

C$.$ float pcdif$($ float, float $)$;

d$.$ None of the above