(3) Question 4 a) Write a tarl-recursive Prolog procedure diff? (L, R) to compute the following [81 L is a list of ordered pairs of the form (a. b), where a and b are integers Rcontains the result when we add all the u's, where u = (b - a) for cach of the ordered pairs in the list L For example Given L = [(4,6). (3, 4), (5, 4)] R=(6 - 4) + (4 - 3) + (4-5) = 2 + 1 - 1 = 2 b) Why is the program in (a) more efficient in terms of space than an alternative program that is not tail-recursive? (3)