It's funny how much intuition plays into these tests. I got 100% on these things, but only because I know when they are speaking English-Logic vs English-Natural, and in this case it's a hybrid of the two languages. The vocabulary and grammar of Natural English, so for example "up" is ambiguous because of how many meanings that word has in English, yet a mix of the very unambiguous rules of Logic and the ambiguous natural rules.
"All rational arguments concerning the economy and the banking crisis must be considered conscientiously. However some of the arguments one hears from economists are clearly not rational.
Conclusion
Therefore one should appreciate that some of the arguments economists propound must not be considered conscientiously."
So the conclusion doesn't follow because it never mentions how you should treat non-rational arguments in the premises. That's English-Logic, which is minimalistic and thus only says exactly what is meant and nothing more. However Natural English is a very exclusive and implicit language, and so in normal speech it's implied that non-rational arguments shouldn't be considered conscientiously by what's been said, it just doesn't literally give you the extra words. As such I find this kind of logic very naive and misleading, especially for those on the autism spectrum, as they might start to interpret Natural English as Logical English, when neither language is actually more logical (Logic is just less noisy for academic and similar purposes).
A similar example is:-
"I filled the tank halfway."
Logical English: "The tank contains at least 50% of whatever goes in it."
Natural English: "The tank contains roughly 50% of whatever goes in it, and no more"
The original question also misleads because the economic nature of the arguments is assumed from previous context in the second sentence and the word "appreciate" shows up in the conclusion, both of which are invalid for Logic but perfectly valid in Natural English.