What pointer is typically maintained to efficiently delete a node by value during a traversal?

• A. A previous pointer to relink the next pointer.
• B. Only the head pointer.
• C. Only the tail pointer.
• D. A separate temp pointer.

Answer: (A)

Keeping a previous pointer as you traverse a singly linked list is essential when you want to delete a node by value. In a singly list, each node only points to the next node, so to remove a target node you must change the link of the node that comes before it. The previous pointer always sits right before the current node, so when you find the node with the matching value you can set previous->next to current->next, effectively bypassing and unlinking the target node in one pass. This works for nodes in the middle or at the head (with a tiny check for updating the head when the target is the first node). Relying only on the head or tail doesn’t give you access to the node that directly precedes the one you want to remove, and a separate temp pointer alone doesn’t fix the linkage without knowing that predecessor.