How do you initialize a linked list?

• A. Set the head and tail pointers to nullptr
• B. Create a sentinel node
• C. Set both head and tail pointers to a dummy node
• D. Do nothing; initialization is automatic

Answer: (A)

Initializing a linked list means establishing a well-defined empty state so the rest of the code can safely build from it. In a typical implementation that keeps both a head and a tail pointer, the cleanest way to represent an empty list is to set both pointers to null. This clearly signals that there are no nodes yet, and it makes future operations straightforward: when you insert the first node, you create it and update both head and tail to point to that node (or update head and then tail if you’re maintaining it). With this setup, checks like “is the list empty?” are simply head == null, and you avoid dereferencing garbage pointers.

Using a sentinel or dummy node is a valid alternative design, but it isn’t the standard initialization that signals emptiness—those approaches start with a node already in the list and adjust how you interpret the head pointer. Similarly, doing nothing leaves pointers uninitialized in many languages, which is unsafe and leads to undefined behavior. So the most direct and robust way to start is to set head and tail to null to represent an empty list.