Hello,
I think you will probably get a 4 because the essay is quite short.
The first paragraph clearly summed up the overall information about the argument. However, personally, I preferred to also bring the source of the information (The argument published in a financial magazine suggest that... ) This is not mandatory, but it is a good way to beef up the essay. Additionally, you concluded that the flaw is that the author fails to demonstrate..... But, in your essay, you stated that the author failed to do several things more than the flaw you mentioned in the first paragraph. So, if I were you, I would just say that, the argument suffers a number of flaws, ranging from AAA to BBB, that would need to be reorganized before a more solid argument could be carried out.
And the reasonings are good, but again, they are both too short. I think you would need to list out some other alternative outcomes or give more examples. I like to add "had the author provided additional material to establish that CCC, the argument would have been strengthened" or sort of sentence at each of the body paragraph!
Lastly, you might want to use the dictionary and find more vocabulary to use in the essay. You used the word "consider" wayyyyyy too much.
I just got a 6.0 on my AWA so these advice are just what I would have done
Hope it helps x