Read the paragraph from a student’s rhetorical analysis essay. At the end of his address on Syria, Obama encourages all Americans to support military action against Syria. He acknowledges America’s role as "the anchor of global security." He then asks people of all political parties, "members of Congress and those of you watching at home tonight," to consider the disturbing images from Syria. He uses a rhetorical question to ask what would happen if Americans chose to ignore this horrible violation of international law.

Which sentence would best add commentary to this paragraph?

a. Obama voices his belief that the United States can stop atrocities without incurring too much risk.
b. Obama ends the speech by stating that the US needs to respond to the violation of international law to maintain power.
c. By reminding the audience that the US has had a central role in keeping the world secure, Obama builds support to maintain peace.
d. By naming the different groups he hopes to persuade, Obama builds pressure to support military action and create a unified response to the atrocities.