tricky CR question

[dadwal.kartik]

Ellen: All three of Shirley's children have the measles!
Lois: As a matter of fact, all three of Shirley's children are fine!

Accepting the assumption that nobody who has measles is fine, which of the following must be true about this exchange?

(A) It is possible that both Ellen and Lois are right about Shirley's children.
(B) It is possible that both Ellen and Lois are mistaken about Shirley's children.
(C) Either Ellen is right about Shirley's children, or Lois is right about them, but they cannot both be right.
(D) Ellen and Lois might both be right about Shirley's children, and they might both be wrong about them.
(E) None of these alternatives correctly identifies the possibilities for this scenario.

OA for this is B.


I found this problem on gmatclub forum. The reason I am posting it here is because I feel this problem can definitely teach us something provided it's a legitimate gmat type problem.

There are couple of concerns about the above problem.

1) Is it even a legit gmat type problem? The moment I was done reading the question stem and glazed over answer choices 'C' felt just too good or to direct, however you want to put it, to be an answer and then I thought something else has to be correct. I started scrutinizing other options but finally settled for C as I couldn't reason any other problem to be true. After looking at OA. I felt what is this question trying to test exactly??
Is it testing if I can fall for too good of an answer, which I finally did or something else.

2) Does gmat even would even answer choices which look ridiculously perfectly like C and then make B as the correct answer?

I am really interested in what should we take away from this problem.

Problems like these often just breaks our whole rhythm and make us doubt our approach.

I would really appreciate some thoughtful comments on this by experts.

Thank you so much!

-Kartik

[jlucero]

This is more of a logical argument than a assumption based argument and would be highly unlikely on a GMAT. My guess is this is from an LSAT, which some super-GMAT studier try to use as supplemental material. Feel free to learn how to set up a logical argument, but like learning trigonometry, this really won't be relevant for your GMAT.

[dadwal.kartik]

Hi Joe,

I really appreciate your help here! I won't waste my time on this.

thanks,

-K

[tim]

This is almost certainly an LSAT problem, which should be avoided at all costs when studying for the GMAT. please understand that using practice questions from dubious sources can actually hurt your performance, and be careful which problem sources you use..