Explanation

Daily arguments with opponents who won’t change their mind and dealing with people who make demands are likely to make someone more realistic about the limited prospects of accomplishing something, or less idealistic and quixotic, which are synonyms.

Arguing with others is not likely to make someone less contentious or dialectical, but more so. And nothing here implies that the president’s policies are altruistic or that he is particularly tenacious. Alternatively, you can look at the answer choices. Idealistic and quixotic form one pair, and dialectical and contentious form another, so one of those pairs has to be the right answer.

Hence idealistic, quixotic are correct options!