Converse is a of conversation. a.
Synonym
c.
Origin
b.
Antonym
d.
Variation
CORRECT variation

D. Variation

Explanation:

The word "converse" is a variation of the word "conversation"

When a word is said to be a variation of another word, it means that it was derived from the word and is used in a different form.

To converse is to have a talk with someone

To have a conversation means the same thing.

The only difference is that "converse" is a verb and "conversation" is a noun.

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).