Which of the following is correct implementation to insert a node at start of linked list?

Question

Comments

The correct answer is only B. but both approaches (A and B) seem to be correct

Answer 1

Implementation B, is the correct one. 

If you modify Implementation One following then it will also work correctly.

Node *insert (Node * head, int data){
    Node *newNode = (Node *)malloc(sizeof(Node));
    newNode -> data = data;
    newNode -> next = head;
    head = newNode;
    return head;
}

Implementation B is working correctly just because you are passing the address of head pointer, hence its can be updated from insert function, we do not need to return the value.