How does the use antithesis to advance her purpose in "quilt of a country"?
a. it calls attention to the opposing forces that define america
b. it enables the writer to effectively present and respond to opposing viewpoints
c. it allows the writer to present vivid details to persuade readers
d. it create rhythm, which makes her writing more memorable

the following key ideas correctly express the key sentence.

restate key idea: most people can learn to swim in ten short lessons.

restate key idea: the majority of water-accident victims require mouth-to-mouth breathing.

restate key idea: an empty, tightly closed gallon jug will support a tired swimmer.  

restate key idea: first aid is to prevent accidents as well as assist in rescue.

explanation: the key idea needs to have the same topic as the key sentence (drowning and safety).

the underline word is basically like a prepositional phrase.