How does the narrator in "exhalation" most clearly change from the beginning
to the end of the story?

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).

merry christmas to you, too. may god be with you all in doing your work and just living a great life in general! < 3

the answer is:

magna carta