I don't see the passage, but an antagonist is a villain, or in other words a negative role.
Answer:
(1) An author doing research for a book asked thousands of Americans what made them happy.
Explanation:
It's tempting to say that the main idea is the conclusion of the paragraph, which is stated in sentence (5). However, the main focus of the paragraph is more on the research on what makes American happy, which is detailed by the responses of the research subjects, as well as the conclusion of the research study. If (5) was the main focus, there would be more details about why most of the things that make you happy are simple and free or inexpensive or what the general research about this topic has been, instead of just one study in particular.
It is a system of voting that allows a citizen to individually number and rank all candidates for both houses of parliament according to their preferences. Which means a citizen's vote can still be counted, even if their first choice of candidate is eliminated due to a lack of votes.