Review the detail

roosevelt explains that one of his reasonings for quarantining aggressors is that we have a moral obligation to do so.

which piece of evidence best supports this reasoning?

a. it is because the people of the united states under modern conditions must, for their own future, give thought to the rest of the world.

b. a bishop wrote me the other day: "it seems to me that something greatly needs to be said in behalf of ordinary humanity against the present practice of carrying horrors of war to civilians"

c. the high aspirations expressed in the briand-kellogg peace pact and the hopes for peace thus raised have of late given way to a haunting fear of calamity.

d. some fifteen years ago the hopes of mankind for a continuing era of international peace were raised to great heights when more than sixty nations solemnly pledged themselves not to resort to arms in furtherance of their national aims and policies.