The correct answers are A) people in the city and people in the country. And C) people who are in favor of free silver and people who want the gold standard.
The groups that Brain is drawing a contrast between are people in the city and people in the country. And people who are in favor of free silver and people who want the gold standard.
The text refers to the “Cross of Gold” speech of William Jennings Bryan who was the candidate for the Democratic Party in the presidential election of 1896. Jennings is comparing the status of the ordinary man that works for a salary with the big businessman of the big cities; the small busies owner with the wealthy owner of a big Company.