I'm thinking of C (but not sure).

Key words like "However", "If" and "then" made me think that:
40% GNP increase is only possible if 20% threshold is met. and to survive the collapse, Russia needs to first meet 20% GNP increase threshold.

A) is false because nowhere did it mention ethnic strife.
B) It says 20%, not 40%
D) maybe? but I find it stretched too far.
E) Russia can increase to 40% of its GNP right off the bat and crashes its economy.

I think C is correct because if Russia can meet 40% GNP increase, it has obviously met the 20% threshold.

abhirup1711 wrote:45. To avoid economic collapse, Russia must increase its GNP by 20%. However, due to the structure of its economy, if the 20% threshold is reached, then a 40% increase in GNP is achievable.
Assuming that the above statements are true, which one of the following must also be true?
(A) If ethnic strife continues in Russia, then a 20% increase in GNP will be unattainable.
(B) If a 40% increase in Russia's GNP is impossible, its economy will collapse.
(C) If Russia's GNP increases by 40%, its economy will not collapse.
(D) If the 20% threshold is reached, then a 40% increase in GNP is achievable and a 60% increase is probable.
(E) If Russia's economy collapses, then it will not have increased its GNP by 40%.
Please explain

Inference question. IMO C

This question is very similar to an official LSAT question that I often teach. However this one appears to have originally come from a book called "Master the LSAT"

This is another example of a question that can be diagrammed using formal logic. In fact in that "Master the LSAT" book it is in the "Diagramming" exercise.

Here is the diagram:

"If GNP does not increase by 20% then Russia's economy will collapse. But if 20% is possible the 40% is achievable. So "NOT 20% increase ---> economy collapse" and "IF 20% reached ---> 40% possible" Take the contrapositive of that last statement "If 40% is NOT possible ---> 20% is NOT reached."

If you put these together we can say "If a 40% increase in GNP is not achievable (then the 20% did not happen) and the economy will collapse. OR "If 40% is NOT possible ---> 20% is NOT reached -- > economy collapse."

This is exactly what choice B states. I checked the original source and this is the official answer.

The other choices are not "must be true." Remember this is an inference question and the correct answer must be true.

A) We are not told what circumstances lead to the 20% being attainable so this is out of scope.

C) We are not told that there is any circumstance where Russia's economy will not collapse. We are told that it WILL collapse without a 20% growth but does this means that if this 20% is attained they are safe? No. What if inflation is 100%? What if there is a civil war? You see you must stick to what it is said and not what you think was said. This is true for the GMAT as well. The argument only tells us that without a 20% increase the economy will collapse and does not tell us what other factors are needed to avoid a collapse so any statement that says something will lead to avoiding the collapse is out of scope.

D) Where does the 60% come from? This is clearly out of scope.

E) This is not true either. The economy might collapse for other reasons even if the GNP increases by 40%.

This is another question that is a little beyond what you would see on the GMAT, but that provides a couple of good lessons that you can apply - like sticking to what the argument actually says! Here is a link to the companion question to this that I also diagrammed. https://www.beatthegmat.com/actors-t154726.html

Hope it helps! David