I would say a. sioux indian attacks on stagecoach lines.
The French concentrated in exploring Canada because they already had forts in it in Quebec and in other parts of Canada, also there wasn't too much fighting over Canada except for the British so they decided to explore Canada.
The main reason why the twenties are sometimes called an "age of prosperity", especially in the United States, is that "<span>A.Incomes throughout the United States grew and the middle class held most of the wealth," due mostly to speculation in the stock market. </span>
