When adding an entry to an array-based implementation of the ADT list at the end of the list a. no shift is necessary b. all of the previous elements must be shifted toward the front of the array C. only one element is shifted toward the end of the array to make room d. only one element is shifted toward the beginning of the array to make room When deleting an entry from an array-based implementation of the ADT list at the end of the list a. no shift is necessary b. all of the previous elements must be shifted toward the front of the array C. only one element is shifted toward the end of the array to close the gap d. only one element is shifted toward the beginning of the array to close the gap