Data structures C++

What is the problem in this enqueue function ?

Select one:

a. QueueFront doesn't always point to the first element

b. New element doesn't be pointed

c. This function works without any problem

d. QueueEnd doesn't always point to the last element

class QueueLL private: struct Node int key; Node next; Node* queueFront; Node* queueEnd; public: QueueLL ) ueueLL() bool isEmpty); void enqueue (int key) void dequeue) int peek ) void printq); void QueueLL:enqueue (int key) Node *nn - new Node; nn-key- key; nn->next nullptr ; if (isEmpty )) I queueFront- nn; queueEnd- nn; else queueEna->next = nn