Select all true statements. A. You can prove a statement P(n) for all positive integers n by showing P(1) and for all positive integers n. B. You prove a statement P(n) by induction for all positive integers n by showing P(1) and by showing that if P(k) is true for all positive integers k, then P(k 1) must also be true. C. In an inductive proof, you always obtain the statement P(n 1) by adding n to both sides of P(n). D. If P(n) is a statement that is false for some, or even all, positive integers n , it is still possible that holds for all positive integers n. E. If you prove P(1), P(2) and for all positive integers n, then you have justified P(n) for all postive integers n F. The Fibonacci sequence is big-Omega of