6. What is used to start accessing a linked chain of nodes? a. The head pointer b. item[0) c. item(1] d. The null pointer 7. What value should headPtr contain if there are no nodes for it to point to? a. b. c. d. The boolean value TRUE nullptr The constant ZERO The constant NULL 8. Each method for the aray based implementation of the ADT bag will require acc of entries and what else? The number of fields a. b. The current number of entries in the bag c. d. The ID of the previous bag entry The ID of the next bag entry 9. Given the following poorly written code sequence headPtr - new Node