Q1: Choose only three of the following theories and provide proof. Do not use the same proof approach more than once (use direct, contrapositive, or contradiction). Justify your choice of proof approach for each theory. A. If n is an even integer, then 3n 1 is an odd integer. B. If 5x 7 is odd, then 9x + 2 is even C. 11x 7 is even if and only if x is odd..