Suppose there is a relation r (A, B, C), with a B+-tree index with search key (A,B). what is the worst-case cost of finding records satisfying 10< A < 50 using this index, in terms of the number of records retrieved n1 and the height h of the tree ?What is the worst-case cost of finding records satisfying 10< A< 50 ^ B < 10 using this index, in terms of the number of records n2 that satisfy this selection , as well as n1 and h defined above ?Under what conditions on n1 and n2 would the index be an efficient way of finding records satisfying 10< A < 50 ^ 5 < B< 10?