1.Double quotation marks are used: a. Double quotation marks are not used at all.
b. whenever there is a direct quotation.
c. For internal dialogues. ​

im kind of confused with what this is asking.

Explanation:

quotation marks, in general, are used for a direct quote

when someone is speaking within the quote, you use one quotation mark (').

Ex.  According to the author, "'The dog was blue,' said Sally." (Collins 2)

That is an internal dialogue^

hope this helped, sorry :)

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).