I'm not sure what you're referring to.
I just tried that lesson and clicked on (C) and never heard Noah say I was right. He started breaking down the core; we went to the hint room, etc.
When he actually went through the answers, his reaction to (C) was, "This actually weakens". Maybe there was just some weird glitch when you did it.
The correct answer is (E).
If you'd like to read / think more about the problem, here's the thread. Feel free to add any questions you have if you're still feeling misgivings about it.
https://www.manhattanprep.com/lsat/foru ... t1279.html