#22 - Local, Must Be True

[Dave Killoran]

Complete Question Explanation
(The complete setup for this game can be found here: lsat/viewtopic.php?t=3405)

The correct answer choice is (B)

Any organism responding to exactly two of the antibiotics must respond in accordance with one of the following two scenarios:

J93_Game_#4_#22_diagram 1.png

Since G is found in both of the scenarios, it follows that any organism responding to two of the antibiotics must respond to G. Therefore, (B) is the correct answer choice.

[Boomer]

Why is A incorrect? If an organism responds to F, it gets G, so couldnt two organisms just have F and G, hence respond to two of the antibiotics?

[KelseyWoods]

Hi Boomer!

Yes, if an organism responds to F, it would get G meaning that you could have an organism with F and G as its 2 antibiotics. However, it is not true that an organism with 2 antibiotics must respond to ferromycin because there is also another possible antibiotic pair that an organism could have.

If an organism responds to 2 out of the 3 antibiotics, there are 2 antibiotic pairing possibilities for that organism:

Possibility #1: F & G
Possibility #2: G & H

We can't have the F & H pairing because we can't have F without G. But note that it's okay to have G without F (careful not to fall for the Mistaken Reversal!) so the G & H pairing works fine. Therefore, an organism can have 2 antibiotics (G & H) without having F.

So if an organism responds to 2 antibiotics, it has to respond to either F & G or G & H. In either case, the organism must respond to G, but could respond to either F or H.

Hope this helps!

Best,
Kelsey