In the proof that the sum of the first n squares is 6n(n+1)(2n+1), we showed P(0) and then P(k)P(k+1) for all k0. Which of the following modifications to the proof would suffice to prove the original claim? a) Show P(0) and P(k1)P(k) for all k1. b) Show P(0),P(1) and P(k)P(k+1) for all k0. c) Show P(0) and P(k+1)P(k+2) for all k0. d) Show P(0) and P(k+1)P(k+2) for all k1