I understood why D was correct by putting it in this context

Imagine saying that " if a successful flying machine was made it would prove that machines can fly or flying doesn't involve flapping wings. Either case the conception of how birds work would change."

Well airplanes do exist, and the flaw here is that the mechanism of how the planes work isn't being considered (flying with engines). Considering planes fly with engines (not flapping wings) would weaken a conclusion that this would impact how birds work.

Same reasoning applies here. By considering that chess-computers wouldn't take a human approach, that means the mechanism is different. Hence the argument is flawed since we can't say the concept of human intelligence would change.

@DeborahAdel I think it's just there way of making it clear that they are negating the statement /(...). So it will look clearer

@ep2127 Hey I'm somewhat near the area and am interested in studying. Let me know if you're inteerested