How is tone affected by word choice

The exact words that you choose affect tone, attitude, imagery, and, voice. Just as with your speaking tone, your written tone can reveal any emotion or attitude a person can feel. Tone can be positive or negative, happy or sad, angry or peaceful, hopeful or desperate, and so on.

a. all of the other answers have at least one capitalization error.

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).