void stack: :do$()$

$\{$

for$($int $i=0$;$i$ topindex$/2$; $i++)$

$\{$T temp$=$entry$[$i$]$;

entry $[$i$]=$entry $[$topindex$-$i$-1]$ ;

entry $[$topindex$-1-$i$]=$temp;

$\}$

$\}$

What is this method do$?$

a$.$ Reverse the stack

b$.$ Doesn't do any thing

c$.$ Replace each item in the stack with the next item

d$.$ Swap the first item with the last one in the stack