Array List Operations That Were Studied Included Adding/removing an Element

Multiple Choice

Array list operations that were studied included adding/removing an element at the end or in the middle, and retrieving the kth element. Which of the following statements about these array list operations is correct?

A) The least expensive operation of an array list is to add an element at the end.
B) The least expensive operation of an array list is to remove an element at the end.
C) The least expensive operation of an array list is to add an element in the middle.
D) The least expensive operation of an array list is to retrieve an arbitrary element.