D) to spread democracy throughout the United States
Panama Canal is the waterway that joins the Caribbean with the Pacific
"... the chief business of the American people is business." he once said.
Coolidge followed a laissez-faire economic policy, whereby the government doesn't interfere in the national economy unless absolutely necessary, and even then its actions should be limited to gentle nudges to get the economy back on track rather than large scale intervention.
So, Coolidge's attitude toward business was 'if it's not broken, don't fix it' - leave business alone to prosper.
The best response would be something that is not on this list: "feudalism," although if you must pick from these options it would be "<span>Manorialism," since this is a subcategory of feudal society. </span>