You are part of a sales group that has been asked to give a presentation. Before you begin, what should you and your group do?
O A. Figure out who is the best public speaker.
O B. Look into file-sharing options so that everyone can work on the
same file at the same time.
OC. Buy the best software on the market.
O D. Ask if you have to give a slide presentation.

Suppose there is a relation r(a, b, c) with a b+-tree index with search keys (a, b).1. what is the worst-case cost of finding records satisfying 10 < a < 50 using this index, in terms of the number of records n1, retrieved and the height h of the tree? 2. what is the worst-case cost of finding records satisfying 10 < a < 50 and 5 < 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? 3. under what conditions on n1 and n2, would the index be an efficient way of finding records satisfying the condition from part (2)?