Given a stack implemented with singly$-$linked nodes where the top of the stack has been placed in

the most optimal location, which of the following operations MUST be done when

is

called?

top.setNext$($null$)$;

$T$ prevTop $=$ top.getData$()$;

$\frac{\frac{?}{?}}{s}$omething else occurs

return prevTop;

LinkedNode $($:$T$:$)$ newTop $=$ head;

while $($newTop$.$getNext$()!=$ top$)$ newTop $=$ newTop.getNext$()$;