void stack::do$()\{$

for$($int i$=0.$ itopindex$/2$;i$++)\{$

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

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

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

$\}$

Assume the stack is array based. What is this method do$?$

a$.$ swap the first item with last item

b$.$ reverse the stack

c$.$ replace each item with next item value

d$.$ doesn't do any thing