To support removal of the last returned element for a singly linked list, which approach is correct?

• A. Maintain previous and current pointers; on remove, set prev.next = current.next; if removing head, update head; set current = prev.next.
• B. Keep only a current pointer; remove by setting current = current.next.
• C. Use a tail pointer to track last removed; remove by tail.next = null.
• D. Maintain a separate 'lastReturned' pointer and adjust its next.

Answer: (A)

Removing the element just returned during a singly linked list traversal requires knowing the node that directly precedes it so you can fix the links. You need access to both the previous node and the current (the last returned) node: update previous.next to current.next, and if the element is the head, update the head to current.next. After unlinking, move the current reference to the node after the removed one, which is previous.next (or the new head if you removed the first element). This approach keeps the list connected and allows the iteration to continue correctly.

Using only a single current pointer doesn’t give you a way to fix the predecessor’s link, so removal would break the chain. A tail pointer doesn’t help with removing an interior element. A separate lastReturned pointer by itself doesn’t provide access to the node before the last returned, so it can't rewire the previous link or handle removal of the head.