In 1830, the French king Charles X /.

The right choice is:

They feared war would cost lives and hurt American business in Europe.

Explanation:

There have always been isolationist feelings in the United States, even since the foundation of the republic. After the outbreak of WWI, the American public did not feel warm about the war, seen as a distant conflict of greedy European powers in which the US had no business. Geographic isolation of the American continent and the natural barrier of huge oceans have traditionally given the country a feeling of safety. People did not see why American lives would be lost and feared damage to American business interests.