Hello. You did not say what text this question refers to, which makes it impossible for the question to be answered accurately. However, to try to help you, I will show you how you can find the main argument of a text. I hope this helps.
The main argument of a text is usually found in the first sentence of the text, with the other phrases being used to support and prove the relevance of the argument and the accuracy it has. It can happen the other way around too, and the main argument is in the last sentence.
In short, an author's main argument in the text is the idea he is defending. This idea can be identified because the author is positioning himself on something, showing something that must be observed.
