Suppose we wanted to use mathematical induction to prove that for each natural number j=1njnn In our induction step, what would we assume to be true and what would we prove to be true. Select one: Assume: k!kkj=1k+1j(k+1)(k+1)k Assume: j=1kjkk Prove: j=1k+1j(k+1)k Assume: kkk! Prove: (k+1)k(k+1) ! j=1kjk(k1)j=1k+1j(k+1)((k+1)1)