True or False? If a DoublelinkedSeq object has no current element, then cursor and precursor should both be null. Select one: True O False True or False? If the first element of a DoublelinkedSeq container is its current item, then cursor references that item and so does precursor. Select one: O True O False True or False? Regardless of whether there was a current element prior to a call to addBefore() or addAfter() on a DoublelinkedSeq container, the newly added element becomes its current element. Select one: O True O False True or False? When two DoublelinkedSeq objects are concatenated using the static method DoublelinkedSeq.concatenate(), there will be no current element in the returned DoublelinkedSeq object. True or False? If advance() moves cursor off the end of a DoublelinkedSeq container, then both cursor and precursor should become null. Select one: True O False True or False? If you used a doubly-linked list for your implementation of the DoublelinkedSeq class, you would not need to maintain the instance variable, precursor. Select one: O True O False In section 4.6 the author tells you that the add() methods on the Java ArrayList and LinkedList classes never fail and thus never return false, but that the add() method for a HashSet may fail. Why might the add() method fail on a HashSet? Select one: O a. the item being added may be a duplicate O b. the element may be of the wrong type O c. HashSets cannot be as large as ArrayLists and LinkedLists d. HashSets cannot contain primitive elements