Why should running your unit test suites not take a long time?A. Unit tests aren't that important, so less time should be spent on them and more time coding. B. Unit tests suites that take too long to run discourages running the tests, making them less usefulC. When running tests in a central location, longer tests can block others from running their tests as wellD. Tests that run too long risk slowing down the feedback cycle for developers

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)?