Assume you're proving that integer derived in certain manner is even, and that you're at the point in the proof which you've the integer expressed as 7(4k2 + 4k + 1) + 1. How should you rewrite this expression to show that the integer is even?
28k2 + 28k + 7 + 1
28k2 + 28k + 8
20(k2 + k) + 8(k2 + k + 1)
2(14k2 + 14k + 4)