Answer: The author's main argument is the topic of the text.
Explanation: The topic of the text is the main story line of the whole argument itself helping the author's personal experience.
The 4th one is correct! :)
could you add me as best answer?
Something that is argueable is debateable.
Answer: A.
The first paragraph explains how the system functions, and the second paragraph describes how the system has succeeded.
Explanation: A because just took the question.