PT39.S4.Q23 - law of supply and demand

Brightfires0121

My problem on this Q is that I can exclude the other four wrong answer choices, but I can't find the right answer choice right either.

Here is my thought:

The premise: no free market economy -> the maximum total utility is not assured;

The conclusion: a country is not trying to bring about a free market economy -> the country is not acting in the way most likely to bring about the maximum total utility.

The right answer choice: the argument wrongly presumes that trying to bring about a condition that will assure the achievement of an end -> the way most likely to achieve that end.

However, if I put this presumption back to the argument, what is negated in the argument is the sufficient condition here ( to assure the achievement of an end is not satisfied ). This negation doesn't get to the argument's conclusion, which is the negation of the necessary condition in the answer choice ( not the way most likely to achieve that end). So I feel the right answer choice should be like "wrongly presumes that the way most likely to achieve max utility -> trying to bring about a condition that will ensure its achievement."

Could anyone give some light?
http://7sage.com/lsat_explanations/lsat-39-section-4-question-23/