John Calvin Coolidge Jr. (1872-1933) was the 30th President of the United States between 1923 and 1929.
He defended a smaller role of goverment and the adoption of <em>laissez-faire </em>policies, giving to the markets the power to make the main economic decisions. Therefore, he was against an active goverment, involved in the economic issues.
<u>The quotation mentioned in option A</u>, refers exactly to laissez-faire, to people (economic agents) participating on the markets solely minding their own business, and the mechanism to reach economic progress and development.
