Failure to rotate crops depletes the soil's nutrients gradually unless other preventive measures are taken. If the s...

Farnoush on October 17 at 08:51PM

Why C?

Could you please explain why C. Thank you

1 Reply

Irina on October 17 at 10:06PM

@Farnoushsalimian,

Let's look at the structure of the argument.

Failure to rotate (FR) crops depletes the soil's nutrients (DN) unless other preventative measures (PM) are taken.

~DN -> PM v ~FR
FR & ~PM -> DN

If the nutrients are depleted (DN), additional crops (AC) cannot be grown unless fertilizer (F) s applied to the soil.

DN ^ ~F -> ~AC
AC -> ~DN v F

If vegetables are grown in soil that had fertilizer (F) applied, they are more vulnerable to pests and must be treated with pesticides (P).

F- > P
~P -> ~F


The question tells us that some vegetables were grown in soil to which fertilizer has never been applied, in other words, it saying if ~F is true and AC is true, what can we infer from the stimulus?

We see from the premise (2) that:

(1) AC-> ~DN v F
(2) ~F
(3) ~DN
(4) PM v ~FR

Since no fertilizer is applied (F is false), we can conclude that the soil must be not depleted of nutrients, and from premise (1) we can conclude that either the crops were rotated or other preventative measures are taken. Since we have no additional information to determine whether the crops were rotated or other preventative measures were taken, but we know that nutrients must not have been depleted, we can conclude that (C) is the correct answer.

Let me know if you have any other questions.