mundasingh123 wrote:Didnt Check OA . C . Since I couldnt get the last 2 Crs that u posted right .I will give my Expln later

gmatmachoman wrote:B can be a strengthener!!

C cannot be a strengthener becox it just talks about "alertness". But the Vitaplus does infact makes the user more energetic & more alertful.

Here in C what if the users are "already" more energetic than the national average?? What if the "more energy" induces "more alertness" on the users?? Now that u can see hidden points in C can "tacitly" weaken the stated cause.

Whereas B , it talks more about the selection of the users. It just says, there is no BIAS in the selection of users.
Going forward, it adds that the Vitaplus is NOT served for free.

B is a very subtle strengthener. C is NOT!!

lunarpower wrote:yeah, this is a horrible question.
i looked up the source on the american version of google books, and checked out the answer key -- and, oh my sweet Lord, these people have no idea how strengthening/weakening questions work.

for instance, choice (c) is an obvious strengthener -- we don't actually know that the levels have increased without this additional information.
...but the answer key tries to eliminate that choice on the grounds that "it is not sufficient to show that vita-plus caused any differences". this is quite disturbing -- it shows that the authors of this book literally don't understand how this type of question is supposed to work! "strengthen" answers are practically never sufficient to show things, and they generally aren't strong enough to prove that something is true; astonishingly, it appears that the authors of this book don't know this.

in reality, (c) and (e) are obvious strengtheners.

also, you should run away from this book as fast as you can, since it's clear that the authors don't sufficiently understand what they're supposed to be doing.