Is A correct because it sounds the strongest of the choices? I chose it by linking the views of the delegates with "not strong enough"(line 15), "strengthen" (line 18), but I am not sure whether I'm on the right track.

I got stuck between (C) and (D). Can someone help to clarify that why choice (D) is wrong?

Can anyone help to explain why choice (A) is wrong? Thanks a lot!

I read the argument all over again. This time the reason why choice A is wrong is clear. The doctor says "half of the members of the group" got the slipped disks. So if the disk problem is sufficient to cause pain, these people should feel the pain!!! So it obviously is not sufficient to p...

Thanks farhadshekib!