What does this code do$?$

public void F$()\{$

Node curr $=$ head;

while $($curr $!=$ null$)\{$

if $($curr$.$next $!=$ null && curr.value $==$ curr.next.value$)\{$

curr.next $=$ curr.next.next$)$;

$\}$ else $\{$

curr $=$ curr.next; $\}\}$

a$.$ Removes duplicates from linked$-$list.

b$.$ Empty linked$-$list.

c$.$ Sorts linked$-$list in ascending order.

d$.$ Removes last element in linked$-$list.